Aqueous polyurethane-polyurea dispersion and aqueous base paint containing said dispersion

ABSTRACT

The present invention relates to an aqueous polyurethane-polyurea dispersion (PD) having polyurethane-polyurea particles, present in the dispersion, having an average particle size of 40 to 2000 nm, and having a gel fraction of at least 50%, obtainable by 
     (I) preparing a composition (Z) comprising, based in each case on the total amount of the composition (Z), 
     (Z.1) 15 to 65 wt % of at least one intermediate containing isocyanate groups and having blocked primary amino groups, its preparation comprising the reaction
         (Z.1.1) of at least one polyurethane prepolymer containing isocyanate groups and comprising anionic groups and/or groups which can be converted into anionic groups, with   (Z.1.2) at least one polyamine comprising at least two blocked primary amino groups and at least one free secondary amino group,   by addition reaction of isocyanate groups from (Z.1.1) with free secondary amino groups from (Z.1.2),       

     (Z.2) 35 to 85 wt % of at least one organic solvent which possesses a solubility in water of not more than 38 wt % at a temperature of 20° C., 
     (II) dispersing the composition (Z) in aqueous phase, and 
     (III) at least partly removing the at least one organic solvent (Z.2) from the dispersion obtained in (II). 
     The present invention also relates to basecoat materials comprising the dispersion (PD), and to multicoat paint systems produced using the basecoat materials.

The present invention relates to an aqueous polyurethane-polyureadispersion (PD) and also to a pigmented aqueous basecoat materialcomprising the dispersion (PD). The aqueous dispersion (PD) isobtainable by (I) preparing a specific composition (Z) comprising aspecific intermediate containing isocyanate groups and also a specificsolvent, (II) dispersing the composition (Z) in aqueous phase, and (III)at least partly removing the organic solvent from the dispersionobtained in (II). The present invention also relates to a process forpreparing the stated dispersion, and also to the use of the dispersion,or of an aqueous basecoat material comprising the dispersion, forimproving the performance properties of basecoat materials and coatingsproduced using the basecoat material. Especially in connection with theconstruction of multicoat paint systems, the dispersion (PD), and alsothe aqueous basecoat material comprising this dispersion, possessoutstanding performance properties.

PRIOR ART

Multicoat paint systems on a wide variety of different substrates, asfor example multicoat paint systems on metallic substrates within theautomobile industry, are known. In general, multicoat paint systems ofthis kind comprise, viewed from the metallic substrate outward, anelectrocoat, a layer which has been applied directly to the electrocoatand is usually referred to as the primer-surfacer coat, at least onecoat which comprises color pigments and/or effect pigments and isgenerally referred to as the basecoat, and a clearcoat. The basiccompositions and functions of these layers and of the coatingcompositions needed to form these layers, i.e. electrocoat materials,so-called primer-surfacers, coating compositions which comprise colorpigments and/or effect pigments and are known as basecoat materials, andclearcoat materials, are known. Accordingly, for example, theelectrocoat serves basically to protect the substrate from corrosion.The so-called primer-surfacer coat serves principally for protectionfrom mechanical stress, for example stone-chipping, and additionally tolevel out unevenness in the substrate. The next coat, referred to as thebasecoat, is principally responsible for the creation of estheticproperties such as color and/or effects such as flop, while theclearcoat which then follows serves particularly to impart scratchresistance and the gloss of the multicoat paint system.

Multicoat paint systems of this kind, and also methods for producingthem, are described in, for example, DE 199 48 004 A1, page 17, line 37,to page 19, line 22, or else in DE 100 43 405 C1, column 3, paragraph[0018], and column 8, paragraph [0052], to column 9, paragraph [0057],in conjunction with column 6, paragraph [0039] to column 8, paragraph[0050].

The known multicoat paint systems are already able to meet many of theperformance properties required by the automobile industry. In therecent past, progress has also been made in terms of the environmentalprofile of such paint systems, especially through the increased use ofaqueous coating materials, of which aqueous basecoat materials are anexample.

A problem which nevertheless occurs again and again in connection withthe production of multicoat paint systems lies in the formation ofunwanted inclusions of air, of solvents and/or of moisture, which maybecome apparent in the form of bubbles beneath the surface of theoverall paint system, and may burst open in the course of final curing.The holes that are formed in the paint system as a result, also calledpinholes and pops, lead to a disadvantageous visual appearance. Theamounts of organic solvents and/or water involved, and also the quantityof air introduced as a result of the application procedure, are toogreat to allow the overall amount to escape from the multicoat paintsystem in the course of curing, without giving rise to defects.

Another important quality of coating materials is an appropriaterheological behavior (application behavior), specifically a pronouncedstructural viscosity. This structural viscosity exists when the coatingmaterial has a viscosity on the one hand, during the application process(generally spray application) with the high shearing that then exists,which is so low that it can be reasonably atomized, and then, on theother hand, following application to the substrate, with the lowshearing that then exists, has a viscosity which is high enough that thecoating material is sufficiently sag-resistant and does not run from thesubstrate or form runs.

The environmental profile of multicoat paint systems is also still inneed of improvement. A contribution in this respect has, indeed, alreadybeen achieved through the replacement of a significant fraction oforganic solvents by water in aqueous paints. A significant improvement,nevertheless, would be achievable by an increase in the solids contentof such paints. However, especially in aqueous basecoat materials, whichcomprise color pigments and/or effect pigments, it is very difficult toincrease the solids content while at the same time maintainingacceptable storage stability (settling behavior) and appropriaterheological properties, or pronounced structural viscosity. In the priorart, accordingly, the structural viscosity is often achieved through theuse of inorganic phyllosilicates. Although the use of such silicates canresult in very good properties of structural viscosity, the coatingmaterials in question are in need of improvement with regard to theirsolids content.

The properties of coating materials or paints, examples being aqueousbasecoat materials, are critically determined by the components theycontain—for example, by polymers employed as binders.

The prior art, accordingly, describes a wide variety of specificpolymers, their use in coating materials, and also their advantageouseffect on various performance properties of paint systems and coatings.

DE 197 19 924 A1 describes a process for preparing a storage-stabledispersion of polyurethanes containing amino groups, the preparation ofwhich involves reaction of polyurethane prepolymers containingisocyanate groups with specific polyamines that have no primary aminogroups, and involves dispersion in water before or after the reaction.One possible area of application is the provision of coating materials.

DE 31 37 748 A1 describes storage-stable aqueous dispersions ofpolyurethane-polyureas produced, again, by reaction of a polyurethaneprepolymer containing isocyanate groups with a specific polyamine. Onepossible area of application is the provision of coatings on metallicsubstrates.

WO 2014/007915 A1 discloses a method for producing a multicoatautomobile finish, using an aqueous basecoat material which comprises anaqueous dispersion of a polyurethane-polyurea resin. The use of thebasecoat material produces positive effects on the optical properties,in particular a minimizing of gel specks.

WO 2012/160053 A1 describes hydrophilic layer assemblies for medicalinstruments, with aqueous dispersions of polyurethane-polyurea resinsbeing among the components used in producing the assembly.

Likewise described is the use of microgels, or dispersions of suchmicrogels, in various coating materials, in order thereby to optimizedifferent performance properties of coating systems. A microgeldispersion, as is known, is a polymer dispersion in which, on the onehand, the polymer is present in the form of comparatively smallparticles, having particle sizes of 0.02 to 10 micrometers, for example(“micro”-gel). On the other hand, however, the polymer particles are atleast partly intramolecularly crosslinked; the internal structure,therefore, equates to that of a typical polymeric network. Because ofthe molecular nature, however, these particles are in solution insuitable organic solvents; macroscopic networks, by contrast, wouldmerely swell. The physical properties of such systems with crosslinkedparticles in this order of magnitude, often also called mesoscopic inthe literature, lie between the properties of macroscopic structures andmicroscopic structures of molecular liquids (see, for example, G. Nimtz,P. Marquardt, D. Stauffer, W. Weiss, Science 1988, 242, 1671). Microgelsare described with more precision later on below.

DE 35 13 248 A1 describes a dispersion of polymeric micropolymerparticles, the dispersion medium being a liquid hydrocarbon. Preparationinvolves the reaction of a prepolymer containing isocyanate groups witha polyamine such as diethylenetriamine. An advantage cited is theimprovement in the resistance to sagging of coatings which comprise themicropolymer particles.

U.S. Pat. No. 4,408,008 describes stable, colloidal aqueous dispersionsof crosslinked urea-urethanes whose preparation involves reacting aprepolymer—which is in dispersion in aqueous solution, which containsisocyanate groups, and which comprises hydrophilic ethylene oxideunits—with polyfunctional amine chain extenders. The films producedtherefrom possess, for example, good hardness and tensile strength.

EP 1 736 246 A1 describes aqueous basecoat materials for application inthe area of automobile finishing, comprising a polyurethane-urea resinwhich is in dispersion in water and which possesses a crosslinkedfraction of 20% to 95%. This aqueous crosslinked resin is prepared in atwo-stage process, by preparation of a polyurethane prepolymercontaining isocyanate groups, and subsequent reaction of this prepolymerwith polyamines. The prepolymer, in a solution in acetone with a solidscontent of about 80%, is dispersed in water, and then reacted with thepolyamine. The use of this crosslinked resin results in advantageousoptical properties on the part of multicoat paint systems.

DE 102 38 349 A1 describes polyurethane microgels in water, with onemicrogel explicitly produced having a crosslinked gel fraction of 60%.The microgels are used in waterborne basecoat materials, where they leadto advantageous rheological properties. Furthermore, through the use ofthe waterborne basecoat materials in the production of multicoat paintsystems, advantages are achieved in respect of decorative properties andadhesion properties.

As a result of the highly promising performance properties of microgeldispersions, particularly aqueous microgel dispersions, this class ofpolymer dispersions is seen as particularly highly promising for use inaqueous coating materials.

It should nevertheless be noted that the preparation of such microgeldispersions, or of dispersions of polymers having a crosslinked gelfraction as described above, must be accomplished in such a way that notonly do the stated advantageous properties result, but also,furthermore, no adverse effects arise on other important properties ofaqueous coating materials. Thus, for example, it is difficult to providemicrogel dispersions with polymer particles that on the one hand havethe crosslinked character described, but on the other hand have particlesizes which permit an appropriate storage stability. As is known,dispersions having comparatively larger particles, in the range of, forexample, greater than 2 micrometers (average particle size), possessincreased sedimentation behavior and hence an impaired storagestability.

Problem

The problem for the present invention, accordingly, was first of all toprovide an aqueous polymer dispersion which allows advantageousperformance properties to be obtained in aqueous coating materials, moreparticularly basecoat materials. These properties refer in particular toproperties which are manifested ultimately in paint systems, especiallymulticoat paint systems, produced using such an aqueous basecoatmaterial. Qualities to be achieved above all ought to include goodoptical properties, more particularly a good pinholing behavior and goodanti-run stability. The mechanical properties as well, however, such asthe adhesion or the stonechip resistance, ought to be outstanding.However, it was likewise necessary to bear in mind here the fact thatthe aqueous polymer dispersion and basecoat materials produced therefrompossess good storage stability, and that the coating materialsformulated with the dispersion can be produced in an environmentallyadvantageous way, more particularly with a high solids content. In spiteof the high solids content, the rheological behavior of the basecoatmaterials ought to be outstanding.

Technical Solution

It has been found that the problems identified can be solved by means ofan aqueous polyurethane-polyurea dispersion (PD) havingpolyurethane-polyurea particles, present in the dispersion, having anaverage particle size of 40 to 2000 nm, and having a gel fraction of atleast 50%, obtainable by

(I)

preparing a composition (Z) comprising, based in each case on the totalamount of the composition (Z),

(Z.1) 15 to 65 wt % of at least one intermediate containing isocyanategroups and having blocked primary amino groups, its preparationcomprising the reaction

(Z.1.1) of at least one polyurethane prepolymer containing isocyanategroups and comprising anionic groups and/or groups which can beconverted into anionic groups, with

(Z.1.2) at least one polyamine comprising at least two blocked primaryamino groups and at least one free secondary amino group,

by addition reaction of isocyanate groups from (Z.1.1) with freesecondary amino groups from (Z.1.2),

(Z.2) 35 to 85 wt % of at least one organic solvent which possesses asolubility in water of not more than 38 wt % at a temperature of 20° C.,

(II)

dispersing the composition (Z) in aqueous phase, and

(III)

at least partly removing the at least one organic solvent (Z.2) from thedispersion obtained in (II).

The new aqueous dispersion (PD) is also referred to below as aqueousdispersion of the invention. Preferred embodiments of the aqueousdispersion (PD) of the invention are apparent from the description whichfollows and from the dependent claims.

Likewise provided by the present invention are a process for preparingthe aqueous dispersion (PD) of the invention, and also a pigmentedaqueous basecoat material comprising the aqueous dispersion (PD).

The present invention also provides a method for producing multicoatpaint systems using the pigmented aqueous basecoat material, and alsothe multicoat paint systems producible by means of said method. Thepresent invention further relates to the use of the pigmented aqueousbasecoat material for improving performance properties of multicoatpaint systems.

It has emerged that through the use of the dispersion (PD) of theinvention in aqueous basecoat materials, it is possible to achieveoutstanding performance properties on the part of multicoat paintsystems which have been produced using the basecoat materials. Deservingof mention above all are good optical properties, more particularly goodpinholing behavior and good anti-run stability. Also outstanding,however, are the mechanical properties such as the adhesion or thestonechip resistance. At the same time, the aqueous dispersions (PD) andbasecoat materials produced from them exhibit good storage stability.Furthermore, the coating materials formulated with the dispersion can beproduced in an environmentally advantageous way, more particularly witha high solids content.

DESCRIPTION

The aqueous dispersion (PD) of the invention is a polyurethane-polyureadispersion. This means, therefore, that the polymer particles present inthe dispersion are polyurethane-polyurea-based. Such polymers arepreparable in principle by conventional polyaddition of, for example,polyisocyanates with polyols and also polyamines. With a view to thedispersion (PD) of the invention and to the polymer particles itcontains, however, there are specific conditions to be observed, whichare elucidated below.

The polyurethane-polyurea particles present in the aqueouspolyurethane-polyurea dispersion (PD) possess a gel fraction of at least50% (for measurement method, see Example section). Moreover, thepolyurethane-polyurea particles present in the dispersion (PD) possessan average particle size of 40 to 2000 nanometers (nm) (for measurementmethod, see Example section).

The dispersions (PD) of the invention, therefore, are microgeldispersions. Indeed, as already described above, a microgel dispersionis a polymer dispersion in which on the one hand the polymer is presentin the form of comparatively small particles, or microparticles, and onthe other hand the polymer particles are at least partlyintramolecularly crosslinked. The latter means that the polymerstructures present within a particle equate to a typical macroscopicnetwork, with three-dimensional network structure. Viewedmacroscopically, however, a microgel dispersion of this kind continuesto be a dispersion of polymer particles in a dispersion medium, waterfor example. While the particles may also in part have crosslinkingbridges to one another (purely from the preparation process, this canhardly be ruled out), the system is nevertheless a dispersion withdiscrete particles included therein that have a measurable averageparticle size.

Because the microgels represent structures which lie between branchedand macroscopically crosslinked systems, they combine, consequently, thecharacteristics of macromolecules with network structure that aresoluble in suitable organic solvents, and insoluble macroscopicnetworks, and so the fraction of the crosslinked polymers can bedetermined, for example, only following isolation of the solid polymer,after removal of water and any organic solvents, and subsequentextraction. The phenomenon utilized here is that whereby the microgelparticles, originally soluble in suitable organic solvents, retain theirinner network structure after isolation, and behave, in the solid, likea macroscopic network. Crosslinking may be verified via theexperimentally accessible gel fraction. The gel fraction is ultimatelythe fraction of the polymer from the dispersion that cannot bemolecularly dispersely dissolved, as an isolated solid, in a solvent. Itis necessary here to rule out a further increase in the gel fractionfrom crosslinking reactions subsequent to the isolation of the polymericsolid. This insoluble fraction corresponds in turn to the fraction ofthe polymer that is present in the dispersion in the form ofintramolecularly crosslinked particles or particle fractions.

In the context of the present invention, it has emerged that onlymicrogel dispersions with polymer particles having particle sizes in therange essential to the invention have all of the required performanceproperties. Particularly important, therefore, is a combination offairly low particle sizes and, nevertheless, a significant crosslinkedfraction or gel fraction. Only in this way is it possible to achieve theadvantageous properties, more particularly the combination of goodoptical and mechanical properties on the part of multicoat paintsystems, on the one hand, and a high solids content and good storagestability of aqueous basecoat materials, on the other.

The polyurethane-polyurea particles present in the aqueouspolyurethane-polyurea dispersion (PD) preferably possess a gel fractionof at least 60%, more preferably of at least 70%, especially preferablyof at least 80%. The gel fraction may therefore amount to up to 100% orapproximately 100%, as for example 99% or 98%. In such a case, then, theentire—or almost the entire—polyurethane-polyurea polymer is present inthe form of crosslinked particles.

The polyurethane-polyurea particles present in the dispersion (PD)preferably possess an average particle size of 40 to 1500 nm, morepreferably of 100 to 1000 nm, more preferably 110 to 500 nm, and evenmore preferably 120 to 300 nm. An especially preferred range is from 130to 250 nm.

The polyurethane-polyurea dispersion (PD) obtained is aqueous.

The expression “aqueous” is known in this context to the skilled person.It refers fundamentally to a system which comprises as its dispersionmedium not exclusively or primarily organic solvents (also calledsolvents); instead, it comprises as its dispersion medium a significantfraction of water. Preferred embodiments of the aqueous character,defined on the basis of the maximum amount of organic solvents and/or onthe basis of the amount of water, are described later on below.

The aqueous dispersion (PD) can be obtained by a specific three-stageprocess, namely by the process—likewise in accordance with theinvention—for preparing an aqueous dispersion (PD).

In a first step (I), a specific composition (Z) is prepared.

The composition (Z) comprises at least one, preferably precisely one,specific intermediate (Z.1) which contains isocyanate groups and hasblocked primary amino groups.

The preparation of the intermediate (Z.1) involves the reaction of atleast one polyurethane prepolymer (Z.1.1), containing isocyanate groupsand comprising anionic groups and/or groups which can be converted intoanionic groups, with at least one polyamine (Z.1.2), comprising at leasttwo blocked primary amino groups and at least one free secondary aminogroup. The intermediate is therefore preparable by reaction of thecomponents (Z.1.1) and (Z.1.2).

Polyurethane polymers containing isocyanate groups and comprisinganionic groups and/or groups which can be converted into anionic groupsare known in principle. For the purposes of the present invention,component (Z.1.1) is referred to as prepolymer, for greater ease ofcomprehension. This component is in fact a polymer which can be referredto as a precursor, since it is used as a starting component forpreparing another component, specifically the intermediate (Z.1).

For preparing the polyurethane prepolymers (Z.1.1) which containisocyanate groups and comprise anionic groups and/or groups which can beconverted into anionic groups, it is possible to employ the aliphatic,cycloaliphatic, aliphatic-cycloaliphatic, aromatic, aliphatic-aromaticand/or cycloaliphatic-aromatic polyisocyanates that are known to theskilled person. Diisocyanates are used with preference. Mention may bemade, by way of example, of the following diisocyanates: 1,3- or1,4-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate, 4,4′- or2,4′-diphenylmethane diisocyanate, 1,4- or 1,5-naphthylene diisocyanate,diisocyanatodiphenyl ether, trimethylene diisocyanate, tetramethylenediisocyanate, ethylethylene diisocyanate, 2,3-dimethylethylenediisocyanate, 1-methyltri methylene diisocyanate, pentamethylenediisocyanate, 1,3-cyclopentylene diisocyanate, hexamethylenediisocyanate, cyclohexylene diisocyanate, 1,2-cyclohexylenediisocyanate, octamethylene diisocyanate, trimethylhexane diisocyanate,tetramethylhexane diisocyanate, decamethylene diisocyanate,dodecamethylene diisocyanate, tetradecamethylene diisocyanate,isophorone diisocyanate (IPDI), 2-isocyanatopropylcyclohexyl isocyanate,dicyclohexylmethane 2,4′-diisocyanate, dicyclohexylmethane4,4′-diisocyanate, 1,4- or 1,3-bis(isocyanatomethyl)cyclohexane, 1,4- or1,3- or 1,2-diisocyanatocyclohexane, 2,4- or2,6-diisocyanato-1-methylcyclohexane,1-isocyanatomethyl-5-isocyanato-1,3,3-trimethylcyclohexane,2,3-bis(8-isocyanatooctyl)-4-octyl-5-hexylcyclohexene,tetramethylxylylene diisocyanates (TMXDI) such as m-tetramethylxylylenediisocyanate, or mixtures of these polyisocyanates. Also possible, ofcourse, is the use of different dimers and trimers of the stateddiisocyanates, such as uretdiones and isocyanurates. Polyisocyanates ofhigher isocyanate functionality may also be used. Examples thereof aretris(4-isocyanatophenyl)methane, 1,3,4-triisocyanatobenzene,2,4,6-triisocyanatotoluene, 1,3,5-tris(6-isocyanatohexylbiuret),bis(2,5-diisocyanato-4-methylphenyl)methane. The functionality mayoptionally be lowered by reaction with monoalcohols and/or secondaryamines. Preference, however, is given to using diisocyanates, moreparticularly to using aliphatic diisocyanates, such as hexamethylenediisocyanate, isophorone diisocyanate (IPDI), dicyclohexylmethane4,4′-diisocyanate, 2,4- or 2,6-diisocyanato-1-methylcyclohexane, andm-tetramethylxylylene diisocyanate (m-TMXDI). An isocyanate is termedaliphatic when the isocyanate groups are attached to aliphatic groups;in other words, when there is no aromatic carbon present in alphaposition to an isocyanate group.

The prepolymers (Z.1.1) are prepared by reacting the statedpolyisocyanates with polyols, more particularly diols, generally withformation of urethanes.

Examples of suitable polyols are saturated or olefinically unsaturatedpolyester polyols and/or polyether polyols. Polyols used moreparticularly are polyester polyols, especially those having anumber-average molecular weight of 400 to 5000 g/mol (for measurementmethod, see Example section). Such polyester polyols, preferablypolyester diols, may be prepared in a known way by reaction ofcorresponding polycarboxylic acids, preferably dicarboxylic acids,and/or their anhydrides with corresponding polyols, preferably diols, byesterification. It is of course optionally possible in addition, evenproportionally, to use monocarboxylic acids and/or monoalcohols for thepreparation. The polyester diols are preferably saturated, moreparticularly saturated and linear.

Examples of suitable aromatic polycarboxylic acids for preparing suchpolyester polyols, preferably polyester diols, are phthalic acid,isophthalic acid, and terephthalic acid, of which isophthalic acid isadvantageous and is therefore used with preference. Examples of suitablealiphatic polycarboxylic acids are oxalic acid, malonic acid, succinicacid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaicacid, sebacic acid, undecanedicarboxylic acid, and dodecanedicarboxylicacid, or else hexahydrophthalic acid, 1,3-cyclohexanedicarboxylic acid,1,4-cyclohexanedicarboxylic acid, 4-methylhexahydrophthalic acid,tricyclodecanedicarboxylic acid, and tetrahydrophthalic acid. Asdicarboxylic acids it is likewise possible to use dimer fatty acids ordimerized fatty acids, which, as is known, are mixtures prepared bydimerizing unsaturated fatty acids and are available, for example, underthe commercial names Radiacid (from Oleon) or Pripol (from Croda). Inthe present context, the use of such dimer fatty acids for preparingpolyester diols is preferred. Polyols used with preference for preparingthe prepolymers (Z.1.1) are therefore polyester diols which have beenprepared using dimer fatty acids. Especially preferred are polyesterdiols in whose preparation at least 50 wt %, preferably 55 to 75 wt %,of the dicarboxylic acids employed are dimer fatty acids.

Examples of corresponding polyols for preparing polyester polyols,preferably polyester diols, are ethylene glycol, 1,2- or1,3-propanediol, 1,2-, 1,3-, or 1,4-butanediol, 1,2-, 1,3-, 1,4-, or1,5-pentanediol, 1,2-, 1,3-, 1,4-, 1,5-, or 1,6-hexanediol, neopentylhydroxypivalate, neopentyl glycol, diethylene glycol, 1,2-, 1,3-, or1,4-cyclohexanediol, 1,2-, 1,3-, or 1,4-cyclohexanedimethanol, andtrimethylpentanediol. Diols are therefore used with preference. Suchpolyols and/or diols may of course also be used directly for preparingthe prepolymer (Z.1.1), in other words reacted directly withpolyisocyanates.

Further possibilities for use in preparing the prepolymers (Z.1.1) arepolyamines such as diamines and/or amino alcohols. Examples of diaminesinclude hydrazine, alkyl- or cycloalkyldiamines such as propylenediamine and 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, andexamples of amino alcohols include ethanolamine or diethanolamine.

The prepolymers (Z.1.1) comprise anionic groups and/or groups which canbe converted into anionic groups (that is, groups which can be convertedinto anionic groups by the use of known neutralizing agents, and alsoneutralizing agents specified later on below, such as bases). As theskilled person is aware, these groups are, for example, carboxylic,sulfonic and/or phosphonic acid groups, especially preferably carboxylicacid groups (functional groups which can be converted into anionicgroups by neutralizing agents), and also anionic groups derived from theaforementioned functional groups, such as, more particularly,carboxylate, sulfonate and/or phosphonate groups, preferably carboxylategroups. The introduction of such groups is known to increase thedispersibility in water. Depending on the conditions selected, thestated groups may be present proportionally or almost completely in theone form (carboxylic acid, for example) or the other form (carboxylate).One particular influencing factor resides, for example, in the use ofthe neutralizing agents which have already been addressed and which aredescribed in even more detail later on below. If the prepolymer (Z.1.1)is mixed with such neutralizing agents, then an amount of the carboxylicacid groups is converted into carboxylate groups, this amountcorresponding to the amount of the neutralizing agent. Irrespective ofthe form in which the stated groups are present, however, a uniformnomenclature is frequently selected in the context of the presentinvention, for greater ease of comprehension. Where, for example, aparticular acid number is specified for a polymer, such as for aprepolymer (Z.1.1), or where such a polymer is referred to ascarboxy-functional, this reference hereby always embraces not only thecarboxylic acid groups but also the carboxylate groups. If there is tobe any differentiation in this respect, such differentiation is dealtwith, for example, using the degree of neutralization.

In order to introduce the stated groups, it is possible, during thepreparation of the prepolymers (Z.1.1), to use starting compounds whichas well as groups for reaction in the preparation of urethane bonds,preferably hydroxyl groups, further comprise the abovementioned groups,carboxylic acid groups for example. In this way the groups in questionare introduced into the prepolymer.

Corresponding compounds contemplated for introducing the preferredcarboxylic acid groups are polyether polyols and/or polyester polyols,provided they contain carboxyl groups. However, compounds used withpreference are at any rate low molecular weight compounds which have atleast one carboxylic acid group and at least one functional groupreactive toward isocyanate groups, preferably hydroxyl groups. In thecontext of the present invention, the expression “low molecular weightcompound”, as opposed to higher molecular weight compounds, especiallypolymers, should be understood to mean those to which a discretemolecular weight can be assigned, as preferably monomeric compounds. Alow molecular weight compound is thus, more particularly, not a polymer,since the latter are always a mixture of molecules and have to bedescribed using mean molecular weights. Preferably, the term “lowmolecular weight compound” is understood to mean that the correspondingcompounds have a molecular weight of less than 300 g/mol. Preference isgiven to the range from 100 to 200 g/mol.

Compounds preferred in this context are, for example, monocarboxylicacids containing two hydroxyl groups, as for example dihydroxypropionicacid, dihydroxysuccinic acid, and dihydroxybenzoic acid. Very particularcompounds are alpha,alpha-dimethylolalkanoic acids such as2,2-dimethylolacetic acid, 2,2-dimethylolpropionic acid,2,2-dimethylolbutyric acid and 2,2-dimethylolpentanoic acid, especially2,2-dimethylolpropionic acid.

Preferably, therefore, the prepolymers (Z.1.1) are carboxy-functional.They preferably possess an acid number, based on the solids content, of10 to 35 mg KOH/g, more particularly 15 to 23 mg KOH/g (for measurementmethod, see Example section).

The number-average molecular weight of the prepolymers may vary widelyand is situated for example in the range from 2000 to 20 000 g/mol,preferably from 3500 to 6000 g/mol (for measurement method, see Examplesection).

The prepolymer (Z.1.1) contains isocyanate groups. Preferably, based onthe solids content, it possesses an isocyanate content of 0.5 to 6.0 wt%, preferably 1.0 to 5.0 wt %, especially preferably 1.5 to 4.0 wt %(for measurement method, see Example section).

Given that the prepolymer (Z.1.1) contains isocyanate groups, thehydroxyl number of the prepolymer is likely in general to be very low.The hydroxyl number of the prepolymer, based on the solids content, ispreferably less than 15 mg KOH/g, more particularly less than 10 mgKOH/g, even more preferably less than 5 mg KOH/g (for measurementmethod, see Example section).

The prepolymers (Z.1.1) may be prepared by known and established methodsin bulk or solution, especially preferably by reaction of the startingcompounds in organic solvents, such as preferably methyl ethyl ketone,at temperatures of, for example, 60 to 120° C., and optionally with useof catalysts typical for polyurethane preparation. Such catalysts areknown to those skilled in the art, one example being dibutyltin laurate.The procedure here is of course to select the proportion of the startingcomponents such that the product, in other words the prepolymer (Z.1.1),contains isocyanate groups. It is likewise directly apparent that thesolvents ought to be selected in such a way that they do not enter intoany unwanted reactions with the functional groups of the startingcompounds, in other words being inert toward these groups to the effectthat they do not hinder the reaction of these functional groups. Thepreparation is preferably actually carried out in an organic solvent(Z.2) as described later on below, since this solvent must in any casebe present in the composition (Z) for preparation in stage (I) of theprocess of the invention.

As already indicated above, the groups in the prepolymer (Z.1.1) whichcan be converted into anionic groups may also be present proportionallyas correspondingly anionic groups, as a result of the use of aneutralizing agent, for example. In this way it is possible to adjustthe water-dispersibility of the prepolymers (Z.1.1) and hence also ofthe intermediate (Z.1).

Neutralizing agents contemplated include, in particular, the known basicneutralizing agents such as, for example, carbonates,hydrogencarbonates, or hydroxides of alkali metals and alkaline earthmetals, such as LiOH, NaOH, KOH, or Ca(OH)₂ for example. Likewisesuitable for the neutralization and preferred for use in the context ofthe present invention are organic bases containing nitrogen, such asamines, such as ammonia, trimethylamine, triethylamine, tributylamines,dimethylaniline, triphenylamine, dimethylethanolamine,methyldiethanolamine, or triethanolamine, and also mixtures thereof.

The neutralization of the prepolymer (Z.1.1) with the neutralizingagents, more particularly with the nitrogen-containing organic bases,may take place after the preparation of the prepolymer in organic phase,in other words in solution with an organic solvent, more particularly asolvent (Z.2) as described below. The neutralizing agent may of coursealso be added during or before the beginning of the actualpolymerization, in which case, for example, the starting compoundscontaining carboxylic acid groups are neutralized.

If neutralization of the groups which can be converted into anionicgroups, more particularly of the carboxylic acid groups, is desired, theneutralizing agent may be added, for example, in an amount such that aproportion of 35% to 65% of the groups is neutralized (degree ofneutralization). Preference is given to a range from 40% to 60% (formethod of calculation, see Example section).

The prepolymer (Z.1.1) is preferably neutralized as described after itspreparation and before its use for preparing the intermediate (Z.1).

The preparation of the intermediate (Z.1) involves the reaction of theabove-described prepolymer (Z.1.1) with at least one, preferablyprecisely one, specific polyamine (Z.1.2).

The polyamine (Z.1.2) comprises at least two blocked primary aminogroups and at least one free secondary amino group.

Blocked amino groups, as is known, are those in which the hydrogenresidues on the nitrogen that are present inherently in free aminogroups have been substituted by reversible reaction with a blockingagent. In view of the blocking, the amino groups cannot be reacted likefree amino groups, via condensation reactions or addition reactions, andin this respect are therefore nonreactive, thereby differentiating themfrom free amino groups. The reactions known per se for the amino groupsare then evidently only enabled after the reversibly adducted blockingagent has been removed again, thereby producing in turn the free aminogroups. The principle therefore resembles the principle of capped orblocked isocyanates, which are likewise known within the field ofpolymer chemistry.

The primary amino groups of the polyamine (Z.1.2) may be blocked withthe blocking agents that are known per se, as for example with ketonesand/or aldehydes. Such blocking in that case, with release of water,produces ketimines and/or aldimines which no longer contain anynitrogen-hydrogen bonds, meaning that typical condensation reactions oraddition reactions of an amino group with a further functional group,such as an isocyanate group, are unable to take place.

Reaction conditions for the preparation of a blocked primary amine ofthis kind, such as of a ketimine, for example, are known. Thus, forexample, such blocking may be realized with introduction of heat to amixture of a primary amine with an excess of a ketone which functions atthe same time as a solvent for the amine. The water of reaction formedis preferably removed during the reaction, in order to prevent thepossibility otherwise of reverse reaction (deblocking) of the reversibleblocking.

The reaction conditions for deblocking of blocked primary amino groupsare also known per se. For example, simply the transfer of a blockedamine to the aqueous phase is sufficient to shift the equilibrium backto the side of the deblocking, as a result of the concentration pressurethat then exists, exerted by the water, and thereby to generate freeprimary amino groups and also a free ketone, with consumption of water.

It follows from the above that in the context of the present invention,a clear distinction is being made between blocked and free amino groups.If, nevertheless, an amino group individually is specified neither asbeing blocked nor as being free, the reference there is to a free aminogroup.

Preferred blocking agents for blocking the primary amino groups of thepolyamine (Z.1.2) are ketones. Particularly preferred among the ketonesare those which constitute an organic solvent (Z.2) as described lateron below. The reason is that these solvents (Z.2) must be present in anycase in the composition (Z) for preparation in stage (I) of the processof the invention. It has already been indicated above that thepreparation of corresponding primary amines blocked with a ketoneproceeds to particularly good effect in an excess of the ketone. Throughthe use of ketones (Z.2) for the blocking, therefore, it is possible touse the correspondingly preferred preparation procedure for blockedamines, without any need for costly and inconvenient removal of theblocking agent, which may be unwanted. Instead, the solution of theblocked amine can be used directly in order to prepare the intermediate(Z.1). Preferred blocking agents are acetone, methyl ethyl ketone,methyl isobutyl ketone, diisopropyl ketone, cyclopentanone, orcyclohexanone, particularly preferred agents are the ketones (Z.2)methyl ethyl ketone and methyl isobutyl ketone.

The preferred blocking with ketones and/or aldehydes, more particularlyketones, and the accompanying preparation of ketimines and/or aldimines,has the advantage, moreover, that primary amino groups are blockedselectively. Secondary amino groups present are evidently unable to beblocked, and therefore remain free. Consequently a polyamine (Z.1.2)which as well as the at least two blocked primary amino groups alsocontains at least one free secondary amino group can be prepared readilyby way of the stated preferred blocking reactions from a polyamine whichcontains exclusively free secondary and primary amino groups.

The polyamines (Z.1.2) may be prepared by blocking the primary aminogroups of conventional polyamines containing at least two primary aminogroups and at least one secondary amino group. Ultimately suitable areall aliphatic, aromatic, or araliphatic (mixed aliphatic-aromatic)polyamines which are known per se and which have at least two primaryamino groups and at least one secondary amino group. This means that aswell as the stated amino groups, there may per se be any aliphatic,aromatic, or araliphatic groups present. Possible, for example, aremonovalent groups located as terminal groups on a secondary amino group,or divalent groups located between two amino groups.

Aliphatic in the context of the present invention is an epithetreferring to all organic groups which are not aromatic. For example, thegroups present as well as the stated amino groups may be aliphatichydrocarbon groups, in other words groups which consist exclusively ofcarbon and hydrogen and which are not aromatic. These aliphatichydrocarbon groups may be linear, branched, or cyclic, and may besaturated or unsaturated. These groups may of course also include bothcyclic and linear or branched moieties. It is also possible foraliphatic groups to contain heteroatoms, more particularly in the formof bridging groups such as ether, ester, amide and/or urethane groups.Possible aromatic groups are likewise known and require no furtherelucidation.

The polyamines (Z.1.2) preferably consist of at least two blockedprimary amino groups, at least one free secondary amino group, and alsoaliphatically saturated hydrocarbon groups.

Likewise preferably, the polyamines (Z.1.2) possess two blocked primaryamino groups and one or two free secondary amino groups, and as primaryamino groups they possess exclusively blocked primary amino groups, andas secondary amino groups they possess exclusively free secondary aminogroups.

Preferably, in total, the polyamines possess three or four amino groups,these groups being selected from the group consisting of the blockedprimary amino groups and of the free secondary amino groups.

Especially preferred polyamines (Z.1.2) are therefore those whichconsist of two blocked primary amino groups, one or two free secondaryamino groups, and also aliphatically saturated hydrocarbon groups.

Examples of preferred polyamines from which polyamines (Z.1.2) may beprepared by blocking of the primary amino groups are diethylenetriamine,3-(2-aminoethyl)aminopropylamine, dipropylenetriamine, and alsoN1-(2-(4-(2-aminoethyl)piperazin-1-yl)ethyl)ethane-1,2-diamine (onesecondary amino group, two primary amino groups for blocking) andtriethylenetetramine, and also N,N′-bis(3-aminopropyl)ethylenediamine(two secondary amino groups, two primary amino groups for blocking).

To the skilled person it is clear that not least for reasons associatedwith pure technical synthesis, there cannot always be a theoreticallyidealized quantitative conversion in the blocking of primary aminogroups. For example, if a particular amount of a polyamine is blocked,the proportion of the primary amino groups that are blocked in theblocking process may be, for example, 95 mol % or more (determinable byIR spectroscopy; see Example section). Where a polyamine in thenonblocked state, for example, possesses two free primary amino groups,and where the primary amino groups of a certain quantity of this amineare then blocked, it is said in the context of the present inventionthat this amine has two blocked primary amino groups if a fraction ofmore than 95 mol % of the primary amino groups present in the quantityemployed are blocked. This is due on the one hand to the fact, alreadystated, that from a technical synthesis standpoint, a quantitativeconversion cannot always be realized. On the other hand, the fact thatmore than 95 mol % of the primary amino groups are blocked means thatthe major fraction of the total amount of the amines used for blockingdoes in fact contain exclusively blocked primary amino groups,specifically exactly two blocked primary amino groups.

The preparation of the intermediate (Z.1) involves the reaction of theprepolymer (Z.1.1) with the polyamine (Z.1.2) by addition reaction ofisocyanate groups from (Z.1.1) with free secondary amino groups from(Z.1.2). This reaction, which is known per se, then leads to theattachment of the polyamine (Z.1.2) onto the prepolymer (Z.1.1), withformation of urea bonds, ultimately forming the intermediate (Z.1). Itwill be readily apparent that in the preparation of the intermediate(Z.1), preference is given to not using any other amines having free orblocked secondary or free or blocked primary amino groups.

The intermediate (Z.1) can be prepared by known and establishedtechniques in bulk or solution, especially preferably by reaction of(Z.1.1) with (Z.1.2) in organic solvents. It is immediately apparentthat the solvents ought to be selected in such a way that they do notenter into any unwanted reactions with the functional groups of thestarting compounds, and are therefore inert or largely inert in theirbehavior toward these groups. As solvent in the preparation, preferenceis given to using, at least proportionally, an organic solvent (Z.2) asdescribed later on below, especially methyl ethyl ketone, even at thisstage, since this solvent must in any case be present in the composition(Z) to be prepared in stage (I) of the process of the invention. Withpreference a solution of a prepolymer (Z.1.1) in a solvent (Z.2) ismixed with a solution of a polyamine (Z.1.2) in a solvent (Z.2), and thereaction described can take place.

Of course, the intermediate (Z.1) thus prepared may be neutralizedduring or after the preparation, using neutralizing agents alreadydescribed above, in the manner likewise described above for theprepolymer (Z.1.1). It is nevertheless preferred for the prepolymer(Z.1.1) to be neutralized prior to its use for preparing theintermediate (Z.1), in a manner described above, so that neutralizationduring or after the preparation of (Z.1) is no longer relevant. In sucha case, therefore, the degree of neutralization of the prepolymer(Z.1.1) can be equated with the degree of neutralization of theintermediate (Z.1). Where there is no further addition of neutralizingagents at all in the context of the process of the invention, therefore,the degree of neutralization of the polymers present in the ultimatelyprepared dispersions (PD) of the invention can also be equated with thedegree of neutralization of the prepolymer (Z.1.1).

The intermediate (Z.1) possesses blocked primary amino groups. This canevidently be achieved in that the free secondary amino groups arebrought to reaction in the reaction of the prepolymer (Z.1.1) and of thepolyamine (Z.1.2), but the blocked primary amino groups are not reacted.Indeed, as already described above, the effect of the blocking is thattypical condensation reactions or addition reactions with otherfunctional groups, such as isocyanate groups, are unable to take place.This of course means that the conditions for the reaction should beselected such that the blocked amino groups also remain blocked, inorder thereby to provide an intermediate (Z.1). The skilled person knowshow to set such conditions, which are brought about, for example, byreaction in organic solvents, which is preferred in any case.

The intermediate (Z.1) contains isocyanate groups. Accordingly, in thereaction of (Z.1.1) and (Z.1.2), the ratio of these components must ofcourse be selected such that the product—that is, the intermediate(Z.1)—contains isocyanate groups.

Since, as described above, in the reaction of (Z.1.1) with (Z.1.2), freesecondary amino groups are reacted with isocyanate groups, but theprimary amino groups are not reacted, owing to the blocking, it is firstof all immediately clear that in this reaction the molar ratio ofisocyanate groups from (Z.1.1) to free secondary amino groups from(Z.1.2) must be greater than 1. This feature arises implicitly,nevertheless clearly and directly from the feature essential to theinvention, namely that the intermediate (Z.1) contains isocyanategroups.

It is nevertheless preferred for there to be an excess of isocyanategroups, defined as below, during the reaction. The molar amounts (n) ofisocyanate groups, free secondary amino groups, and blocked primaryamino groups, in this preferred embodiment, satisfy the followingcondition: [n (isocyanate groups from (Z.1.1))−n (free secondary aminogroups from (Z.1.2))]/n (blocked primary amino groups from(Z.1.2))=1.2/1 to 4/1, preferably 1.5/1 to 3/1, very preferably 1.8/1 to2.2/1, even more preferably 2/1.

In this preferred embodiment, the intermediate (Z.1), formed by reactionof isocyanate groups from (Z.1.1) with the free secondary amino groupsfrom (Z.1.2), possesses an excess of isocyanate groups in relation tothe blocked primary amino groups. This excess is ultimately achieved byselecting the molar ratio of isocyanate groups from (Z.1.1) to the totalamount of free secondary amino groups and blocked primary amino groupsfrom (Z.1.2) to be large enough that even after the preparation of (Z.1)and the corresponding consumption of isocyanate groups by the reactionwith the free secondary amino groups, there remains a correspondingexcess of the isocyanate groups.

Where, for example, the polyamine (Z.1.2) has one free secondary aminogroup and two blocked primary amino groups, the molar ratio between theisocyanate groups from (Z.1.1) to the polyamine (Z.1.2) in theespecially preferred embodiment is set at 5/1. The consumption of oneisocyanate group in the reaction with the free secondary amino groupwould then mean that 4/2 (or 2/1) was realized for the condition statedabove.

The fraction of the intermediate (Z.1) is from 15 to 65 wt %, preferablyfrom 25 to 60 wt %, more preferably from 30 to 55 wt %, especiallypreferably from 35 to 52.5 wt %, and, in one very particular embodiment,from 40 to 50 wt %, based in each case on the total amount of thecomposition (Z).

Determining the fraction of an intermediate (Z.1) may be carried out asfollows: The solids content of a mixture which besides the intermediate(Z.1) contains only organic solvents is ascertained (for measurementmethod for determining the solids (also called solids content, seeExample section). The solids content then corresponds to the amount ofthe intermediate (Z.1). By taking account of the solids content of themixture, therefore, it is possible to determine or specify the fractionof the intermediate (Z.1) in the composition (Z). Given that theintermediate (Z.1) is preferably prepared in an organic solvent anyway,and therefore, after the preparation, is in any case present in amixture which comprises only organic solvents apart from theintermediate, this is the technique of choice.

The composition (Z) further comprises at least one specific organicsolvent (Z.2).

The solvents (Z.2) possess a solubility in water of not more than 38 wt% at a temperature of 20° C. (for measurement method, see Examplesection). The solubility in water at a temperature of 20° C. ispreferably less than 30 wt %. A preferred range is from 1 to 30 wt %.

The solvent (Z.2) accordingly possesses a fairly moderate solubility inwater, being in particular not fully miscible with water or possessingno infinite solubility in water. A solvent is fully miscible with waterwhen it can be mixed in any proportions with water without occurrence ofseparation, in other words of the formation of two phases.

Examples of solvents (Z.2) are methyl ethyl ketone, methyl isobutylketone, diisobutyl ketone, diethyl ether, dibutyl ether, dipropyleneglycol dimethyl ether, ethylene glycol diethyl ether, toluene, methylacetate, ethyl acetate, butyl acetate, propylene carbonate,cyclohexanone, or mixtures of these solvents. Preference is given tomethyl ethyl ketone, which has a solubility in water of 24 wt % at 20°C.

No solvents (Z.2) are therefore solvents such as acetone,N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, tetrahydrofuran, dioxane,N-formylmorpholine, dimethylformamide, or dimethyl sulfoxide.

A particular effect of selecting the specific solvents (Z.2) of onlylimited solubility in water is that when the composition (Z) isdispersed in aqueous phase, in step (II) of the process of theinvention, a homogeneous solution cannot be directly formed. It isassumed that the dispersion that is present instead makes it possiblefor the crosslinking reactions that occur as part of step (II) (additionreactions of free primary amino groups and isocyanate groups to formurea bonds) to take place in a restricted volume, thereby ultimatelyallowing the formation of the microparticles defined as above.

As well as having the water-solubility described, preferred solvents(Z.2) possess a boiling point of not more than 120° C., more preferablyof not more than 90° C. (under atmospheric pressure, in other words1.013 bar). This has advantages in the context of step (III) of theprocess of the invention, said step being described later on below, inother words the at least partial removal of the at least one organicsolvent (Z.2) from the dispersion prepared in step (II) of the processof the invention. The reason is evidently that, when using the solvents(Z.2) that are preferred in this context, these solvents can be removedby distillation, for example, without the removal simultaneously ofsignificant quantities of the water introduced in step (II) of theprocess of the invention. There is therefore no need, for example, forthe laborious re-addition of water in order to retain the aqueous natureof the dispersion (PD).

The fraction of the at least one organic solvent (Z.2) is from 35 to 85wt %, preferably from 40 to 75 wt %, more preferably from 45 to 70 wt %,especially preferably from 47.5 to 65 wt %, and, in one very particularembodiment, from 50 to 60 wt %, based in each case on the total amountof the composition (Z).

In the context of the present invention it has emerged that through thespecific combination of a fraction as specified above for theintermediate (Z.1) in the composition (Z), and through the selection ofthe specific solvents (Z.2) it is possible, after the below-describedsteps (II) and (III), to provide polyurethane-polyurea dispersions whichcomprise polyurethane-polyurea particles having the requisite particlesize, which further have the requisite gel fraction.

The components (Z.1) and (Z.2) described preferably make up in total atleast 90 wt % of the composition (Z). Preferably the two components makeup at least 95 wt %, more particularly at least 97.5 wt %, of thecomposition (Z). With very particular preference, the composition (Z)consists of these two components. In this context it should be notedthat where neutralizing agents as described above are used, theseneutralizing agents are ascribed to the intermediate when calculatingthe amount of an intermediate (Z.1). The reason is that in this case theintermediate (Z.1) at any rate possesses anionic groups, which originatefrom the use of the neutralizing agent. Accordingly, the cation that ispresent after these anionic groups have formed is likewise ascribed tothe intermediate.

Where the composition (Z) includes other components, in addition tocomponents (Z.1) and (Z.2), these other components are preferably justorganic solvents. The solids content of the composition (Z) thereforecorresponds preferably to the fraction of the intermediate (Z.1) in thecomposition (Z). The composition (Z) therefore possesses preferably asolids content of 15 to 65 wt %, preferably of 25 to 60 wt %, morepreferably of 30 to 55 wt %, especially preferably of 35 to 52.5 wt %,and, in one especially preferred embodiment, of 40 to 50 wt %.

A particularly preferred composition (Z) therefore contains in total atleast 90 wt % of components (Z.1) and (Z.2), and other than theintermediate (Z.1) includes exclusively organic solvents.

An advantage of the composition (Z) is that it can be prepared withoutthe use of eco-unfriendly and health-injurious organic solvents such asN-methyl-2-pyrrolidone, dimethylformamide, dioxane, tetrahydrofuran, andN-ethyl-2-pyrrolidone. Preferably, accordingly, the composition (Z)contains less than 10 wt %, preferably less than 5 wt %, more preferablyless than 2.5 wt % of organic solvents selected from the groupconsisting of N-methyl-2-pyrrolidone, dimethylformamide, dioxane,tetrahydrofuran, and N-ethyl-2-pyrrolidone. The composition (Z) ispreferably entirely free from these organic solvents.

In a second step (II) of the process of the invention, the composition(Z) is dispersed in aqueous phase.

It is known, and also follows from what has already been said above,that in step (II), therefore, there is a deblocking of the blockedprimary amino groups of the intermediate (Z.1). Indeed, as a result ofthe transfer of a blocked amine to the aqueous phase, the reversiblyattached blocking agent is released, with consumption of water, and freeprimary amino groups are formed.

It is likewise clear, therefore, that the resulting free primary aminogroups are then reacted with isocyanate groups likewise present in theintermediate (Z.1), or in the deblocked intermediate formed from theintermediate (Z.1), by addition reaction, with formation of urea bonds.

It is also known that the transfer to the aqueous phase means that it ispossible in principle for the isocyanate groups in the intermediate(Z.1), or in the deblocked intermediate formed from the intermediate(Z.1), to react with the water, with elimination of carbon dioxide, toform free primary amino groups, which can then be reacted in turn withisocyanate groups still present.

Of course, the reactions and conversions referred to above proceed inparallel with one another. Ultimately, as a result, for example, ofintermolecular and intramolecular reaction or crosslinking, a dispersionis formed which comprises polyurethane-polyurea particles with definedaverage particle size and with defined degree of crosslinking or gelfraction.

In step (II) of the process of the invention, then, the composition (Z)is dispersed in water, there being a deblocking of the blocked primaryamino groups of the intermediate (Z.1) and a reaction of the resultingfree primary amino groups with the isocyanate groups of the intermediate(Z.1) and also with the isocyanate groups of the deblocked intermediateformed from the intermediate (Z.1), by addition reaction.

Step (II) of the process of the invention, in other words the dispersingin aqueous phase, may take place in any desired way. This means thatultimately the only important thing is that the composition (Z) is mixedwith water or with an aqueous phase. With preference, the composition(Z), which after the preparation may be for example at room temperature,in other words 20 to 25° C., or at a temperature increased relative toroom temperature, of 30 to 60° C., for example, can be stirred intowater, producing a dispersion. The water already introduced has roomtemperature, for example. Dispersion may take place in pure water(deionized water), meaning that the aqueous phase consists solely ofwater, this being preferred. Besides water, of course, the aqueous phasemay also include, proportionally, typical auxiliaries such as typicalemulsifiers and protective colloids. A compilation of suitableemulsifiers and protective colloids is found in, for example, HoubenWeyl, Methoden der organischen Chemie [Methods of Organic Chemistry],volume XIV/1 Makromolekulare Stoffe [Macromolecular compounds], GeorgThieme Verlag, Stuttgart 1961, p. 411 ff.

It is of advantage if in stage (II) of the process of the invention, inother words at the dispersing of the composition (Z) in aqueous phase,the weight ratio of organic solvents and water is selected such that theresulting dispersion has a weight ratio of water to organic solvents ofgreater than 1, preferably of 1.05 to 2/1, especially preferably of 1.1to 1.5/1.

In step (III) of the process of the invention, the at least one organicsolvent (Z.2) is removed at least partly from the dispersion obtained instep (II). Of course, step (III) of the process may also entail removalof other solvents as well, possibly present, for example, in thecomposition (Z).

The removal of the at least one organic solvent (Z.2) and of any furtherorganic solvents may be accomplished in any way which is known, as forexample by vacuum distillation at temperatures slightly raised relativeto room temperature, of 30 to 60° C., for example.

The resulting polyurethane-polyurea dispersion (PD) is aqueous(regarding the basic definition of “aqueous”, see earlier on above).

A particular advantage of the dispersion (PD) of the invention is thatit can be formulated with only very small fractions of organic solvents,yet enables the advantages described at the outset in accordance withthe invention. The dispersion (PD) of the invention contains preferablyless than 10 wt %, especially preferably less than 5 wt %, verypreferably less than 2.5 wt % of organic solvents (for measurementmethod, see Example section).

The fraction of the polyurethane-polyurea polymer in the dispersion (PD)is preferably 25 to 55 wt %, preferably 30 to 50 wt %, more preferably35 to 45 wt %, based in each case on the total amount of the dispersion(determined as for the determination described above for theintermediate (Z.1) via the solids content).

The fraction of water in the dispersion (PD) is preferably 45 to 75 wt%, preferably 50 to 70 wt %, more preferably 55 to 65 wt %, based ineach case on the total amount of the dispersion.

The dispersion (PD) of the invention consists preferably to an extent ofat least 90 wt %, preferably at least 95 wt %, very preferably at least97.5 wt % of the polyurethane-polyurea polymer and water.

Even more preferred is for the dispersion, other than the polymer, toinclude only water and any organic solvents, in the form, for example,of residual fractions, not fully removed in stage (III) of the processof the invention. The solids content of the dispersion (PD) is thereforepreferably 25% to 55%, preferably 30% to 50%, more preferably 35% to45%, and more preferably still is in agreement with the fraction of thepolymer in the dispersion.

An advantage of the dispersion (PD) is that it can be prepared withoutthe use of eco-unfriendly and health-injurious organic solvents such asN-methyl-2-pyrrolidone, dimethylformamide, dioxane, tetrahydrofuran, andN-ethyl-2-pyrrolidone. Accordingly the dispersion (PD) containspreferably less than 10 wt %, preferably less than 5 wt %, morepreferably less than 2.5 wt % of organic solvents selected from thegroup consisting of N-methyl-2-pyrrolidone, dimethylformamide, dioxane,tetrahydrofuran, and N-ethyl-2-pyrrolidone. The dispersion (PD) ispreferably entirely free from these organic solvents.

Based on the solids content, the polyurethane-polyurea polymer presentin the dispersion preferably possesses an acid number of 10 to 35 mgKOH/g, more particularly of 15 to 23 mg KOH/g (for measurement method,see Example section).

The polyurethane-polyurea polymer present in the dispersion preferablypossesses hardly any hydroxyl groups, or none. The OH number of thepolymer, based on the solids content, is preferably less than 15 mgKOH/g, more particularly less than 10 mg KOH/g, more preferably stillless than 5 mg KOH/g (for measurement method, see Example section).

A further subject of the present invention is a pigmented aqueousbasecoat material (waterborne basecoat material) comprising at leastone, preferably precisely one, aqueous dispersion (PD). All of thepreferred embodiments stated above with regard to the dispersion (PD)also, of course, apply in respect of the basecoat material comprising adispersion (PD).

A basecoat material is a color-imparting intermediate coating materialthat is used in automotive finishing and general industrial painting.This basecoat material is generally applied to a substrate which hasbeen pretreated with a baked (fully cured) primer-surfacer. Substratesused may also include existing paint systems, which may optionallyrequire pretreatment as well (by abrading, for example). To protect abasecoat film from environmental effects in particular, at least oneadditional clearcoat film is generally applied over it. This isgenerally done in a wet-on-wet process—that is, the clearcoat materialis applied without the basecoat film being cured. Curing then takesplace, finally, together with the clearcoat.

The fraction of the dispersions (PD) of the invention, based on thetotal weight of the pigmented aqueous basecoat material, is preferably2.5 to 60 wt %, more preferably 10 to 50 wt %, and very preferably 15 to40 wt % or even 10 to 30 wt %.

The fraction of the polyurethane-polyurea polymers originating from thedispersions of the invention, based on the total weight of the pigmentedaqueous basecoat material, is preferably 1 to 30 wt %, more preferably 4to 25 wt %, and very preferably 6 to 20 wt % or even 8 to 15 wt %.

Determining or specifying the fraction of the polyurethane-polyureapolymers originating from the dispersions of the invention in thebasecoat material may be done via the determination of the solidscontent of a dispersion (PD) of the invention which is to be used in thebasecoat material.

In the case of a possible particularization to basecoat materialscomprising preferred dispersions (PD) in a specific proportional range,the following applies. The dispersions (PD) which do not fall within thepreferred group may of course still be present in the basecoat material.In that case the specific proportional range applies only to thepreferred group of dispersions (PD). It is preferred nonetheless for thetotal proportion of dispersions (PD), consisting of dispersions from thepreferred group and dispersions which are not part of the preferredgroup, to be subject likewise to the specific proportional range.

In the case of restriction to a proportional range of 4 to 25 wt % andto a preferred group of dispersions (PD), therefore, this proportionalrange evidently applies initially only to the preferred group ofdispersions (PD). In that case, however, it would be preferable forthere to be likewise from 4 to 25 wt % in total present of alloriginally encompassed dispersions, consisting of dispersions from thepreferred group and dispersions which do not form part of the preferredgroup. If, therefore, 15 wt % of dispersions (PD) of the preferred groupare used, not more than 10 wt % of the dispersions of the non-preferredgroup may be used.

The stated principle is valid, for the purposes of the presentinvention, for all stated components of the basecoat material and fortheir proportional ranges—for example, for the pigments specified lateron below, or else for the crosslinking agents specified later on below,such as melamine resins.

The aqueous basecoat material of the invention is pigmented, thuscomprising at least one pigment. Such color pigments and effect pigmentsare known to those skilled in the art and are described, for example, inRömpp-Lexikon Lacke and Druckfarben, Georg Thieme Verlag, Stuttgart, NewYork, 1998, pages 176 and 451. The terms “coloring pigment” and “colorpigment” are interchangeable, just like the terms “visual effectpigment” and “effect pigment”.

Useful effect pigments are, for example, platelet-shaped metal effectpigments such as lamellar aluminum pigments, gold bronzes, oxidizedbronzes and/or iron oxide-aluminum pigments, pearlescent pigments suchas pearl essence, basic lead carbonate, bismuth oxide chloride and/ormetal oxide-mica pigments and/or other effect pigments such asplatelet-shaped graphite, platelet-shaped iron oxide, multilayer effectpigments composed of PVD films and/or liquid crystal polymer pigments.Particularly preferred for use at any rate, although not necessarilyexclusively, are platelet-shaped metal effect pigments, moreparticularly plated-shaped aluminum pigments.

Typical color pigments especially include inorganic coloring pigmentssuch as white pigments such as titanium dioxide, zinc white, zincsulfide or lithopone; black pigments such as carbon black, ironmanganese black, or spinel black; chromatic pigments such as chromiumoxide, chromium oxide hydrate green, cobalt green or ultramarine green,cobalt blue, ultramarine blue or manganese blue, ultramarine violet orcobalt violet and manganese violet, red iron oxide, cadmiumsulfoselenide, molybdate red or ultramarine red; brown iron oxide, mixedbrown, spinel phases and corundum phases or chromium orange; or yellowiron oxide, nickel titanium yellow, chromium titanium yellow, cadmiumsulfide, cadmium zinc sulfide, chromium yellow or bismuth vanadate.

The fraction of the pigments may be situated for example in the rangefrom 1 to 30 wt %, preferably 1.5 to 20 wt %, more preferably 2.0 to 15wt %, based on the total weight of the pigmented aqueous basecoatmaterial.

Through the use of the dispersion (PD) and of the polymer presenttherein, the basecoat material of the invention comprises curablebinders. A “binder” in the context of the present invention and inaccordance with relevant DIN EN ISO 4618 is the nonvolatile component ofa coating composition, without pigments and fillers. Specific binders,accordingly, also include, for example, typical coatings additives, thepolymer present in the dispersion (PD), or further polymers which can beused, as described below, and typical crosslinking agents as describedbelow. Hereinafter, however, the expression, for the sake simply ofbetter clarity, is used principally in relation to particular physicallycurable polymers which optionally may also be thermally curable,examples being the polymers in the dispersions (PD), or else differentpolyurethanes, polyesters, polyacrylates and/or copolymers of the statedpolymers.

In the context of the present invention, the term “physical curing”means the formation of a film through loss of solvents from polymersolutions or polymer dispersions. Typically, no crosslinking agents arenecessary for this curing.

In the context of the present invention, the term “thermal curing”denotes the heat-initiated crosslinking of a coating film, with eitherself-crosslinking binders or else a separate crosslinking agent, incombination with a polymer as binder, (external crosslinking), beingused in the parent coating material. The crosslinking agent comprisesreactive functional groups which are complementary to the reactivefunctional groups present in the binders. As a result of the reaction ofthe groups, there is then crosslinking and hence, ultimately, theformation of a macroscopically crosslinked coating film.

It is clear that the binder components present in a coating materialalways exhibit at least a proportion of physical curing. If, therefore,it is said that a coating material comprises binder components which arethermally curable, this of course does not rule out the curing includinga proportion of physical curing as well.

The basecoat material of the invention preferably further comprises atleast one polymer as binder that is different from thepolyurethane-polyurea polymer present in the dispersion (PD), moreparticularly at least one polymer selected from the group consisting ofpolyurethanes, polyesters, polyacrylates and/or copolymers of the statedpolymers, more particularly polyesters and/or polyurethanepolyacrylates. Preferred polyesters are described, for example, in DE4009858 A1 in column 6 line 53 to column 7 line 61 and column 10 line 24to column 13 line 3. Preferred polyurethane-polyacrylate copolymers(acrylated polyurethanes) and their preparation are described in, forexample, WO 91/15528 A1, page 3, line 21 to page 20, line 33, and DE4437535 A1, page 2, line 27 to page 6, line 22. The described polymersas binders are preferably hydroxy-functional and especially preferablypossess an OH number in the range from 20 to 200 mg KOH/g, morepreferably from 50 to 150 mg KOH/g. The basecoat materials of theinvention more preferably comprise at least one hydroxy-functionalpolyurethane-polyacrylate copolymer, more preferably still at least onehydroxy-functional polyurethane-polyacrylate copolymer and also at leastone hydroxy-functional polyester.

The proportion of the further polymers as binders may vary widely and issituated preferably in the range from 0.5 to 20.0 wt %, more preferably1.0 to 15.0 wt %, very preferably 1.5 to 10.0 wt %, based in each caseon the total weight of the basecoat material of the invention.

The basecoat material of the invention preferably further comprises atleast one typical crosslinking agent known per se. It preferablycomprises, as a crosslinking agent, at least one aminoplast resin and/ora blocked polyisocyanate, preferably an aminoplast resin. Among theaminoplast resins, melamine resins in particular are preferred.

The proportion of the crosslinking agents, more particularly aminoplastresins and/or blocked polyisocyanates, very preferably aminoplast resinsand, of these, preferably melamine resins, is preferably in the rangefrom 0.5 to 20.0 wt %, more preferably 1.0 to 15.0 wt %, very preferably1.5 to 10.0 wt %, based in each case on the total weight of the basecoatmaterial of the invention.

Preferably, the coating composition of the invention additionallycomprises at least one thickener.

Suitable thickeners are inorganic thickeners from the group of thephyllosilicates such as lithium aluminum magnesium silicates. It isnevertheless known that coating materials whose profile of rheologicalproperties is determined via the primary or predominant use of suchinorganic thickeners are in need of improvement in terms of their solidscontent, in other words can be formulated only with decidedly low solidscontents of less than 20%, for example, without detriment to importantperformance properties. A particular advantage of the basecoat materialof the invention is that it can be formulated without, or without agreat fraction of, such inorganic phyllosilicates employed asthickeners. Accordingly, the fraction of inorganic phyllosilicates usedas thickeners, based on the total weight of the basecoat material, ispreferably less than 0.5 wt %, especially preferably less than 0.1 wt %,and more preferably still less than 0.05 wt %. With very particularpreference, the basecoat material is entirely free of such inorganicphyllosilicates used as thickeners.

Instead, the basecoat material preferably comprises at least one organicthickener, as for example a (meth)acrylic acid-(meth)acrylate copolymerthickener or a polyurethane thickener. Employed with preference areassociative thickeners, such as the associative polyurethane thickenersknown per se, for example. Associative thickeners, as is known, arewater-soluble polymers which have strongly hydrophobic groups at thechain ends or in side chains, and/or whose hydrophilic chains containhydrophobic blocks or concentrations in their interior. As a result,these polymers possess a surfactant character and are capable of formingmicelles in aqueous phase. In similarity with the surfactants, thehydrophilic regions remain in the aqueous phase, while the hydrophobicregions enter into the particles of polymer dispersions, adsorb on thesurface of other solid particles such as pigments and/or fillers, and/orform micelles in the aqueous phase. Ultimately a thickening effect isachieved, without any increase in sedimentation behavior. Thickeners ofthis kind are available commercially, as for example under the tradename Adekanol (from Adeka Corporation).

The proportion of the organic thickeners is preferably in the range from0.01 to 5.0 wt %, more preferably 0.02 to 3.0 wt %, very preferably 0.05to 3.0 wt %, based in each case on the total weight of the basecoatmaterial of the invention.

Furthermore, the basecoat material of the invention may further compriseat least one further adjuvant. Examples of such adjuvants are saltswhich are thermally decomposable without residue or substantiallywithout residue, polymers as binders that are curable physically,thermally and/or with actinic radiation and that are different from thepolymers already stated as binders, further crosslinking agents, organicsolvents, reactive diluents, transparent pigments, fillers, molecularlydispersively soluble dyes, nanoparticles, light stabilizers,antioxidants, deaerating agents, emulsifiers, slip additives,polymerization inhibitors, initiators of radical polymerizations,adhesion promoters, flow control agents, film-forming assistants, sagcontrol agents (SCAs), flame retardants, corrosion inhibitors, waxes,siccatives, biocides, and matting agents. Such adjuvants are used in thecustomary and known amounts.

The solids content of the basecoat material of the invention may varyaccording to the requirements of the case in hand. The solids content isguided primarily by the viscosity that is needed for application, moreparticularly spray application. A particular advantage is that thebasecoat material of the invention, for a comparatively high solidscontent, is able nevertheless to have a viscosity which allowsappropriate application.

The solids content of the basecoat material of the invention ispreferably at least 25%, more preferably at least 30%, especiallypreferably from 30% to 50%.

Under the stated conditions, in other words at the stated solidscontents, preferred basecoat materials of the invention have a viscosityof 40 to 150 mPa·s, more particularly 70 to 85 mPa·s, at 23° C. under ashearing load of 1000 1/s (for further details regarding the measurementmethod, see Example section). For the purposes of the present invention,a viscosity within this range under the stated shearing load is referredto as spray viscosity (working viscosity). As is known, coatingmaterials are applied at spray viscosity, meaning that under theconditions then present (high shearing load) they possess a viscositywhich in particular is not too high, so as to permit effectiveapplication. This means that the setting of the spray viscosity isimportant, in order to allow a paint to be applied at all by spraymethods, and to ensure that a complete, uniform coating film is able toform on the substrate to be coated. A particular advantage is that evena basecoat material of the invention adjusted to spray viscositypossesses a high solids content. The preferred ranges of the solidscontent, particularly the lower limits, therefore suggest that in theapplicable state, preferably, the basecoat material of the invention hascomparatively high solids contents.

The basecoat material of the invention is aqueous (regarding thedefinition of “aqueous”, see above).

The fraction of water in the basecoat material of the invention ispreferably at least 35 wt %, preferably at least 40 wt %, and morepreferably from 45 to 60 wt %.

Even more preferred is for the percentage sum of the solids content ofthe basecoat material and the fraction of water in the basecoat materialto be at least 70 wt %, preferably at least 80 wt %. Among thesefigures, preference is given to ranges of 70 to 90 wt %, in particular80 to 90 wt %. In this reporting, the solids content, whichtraditionally only possesses the unit “%”, is reported in “wt %”. Sincethe solids content ultimately also represents a percentage weightfigure, this form of representation is justified. If, then, a basecoatmaterial has a solids content of 35% and a water content of 50 wt %, forexample, the percentage sum defined above, from the solids content ofthe basecoat material and the fraction of water in the basecoatmaterial, is 85 wt %.

This means that preferred basecoat materials of the invention containcomponents that are in principle a burden on the environment, such asorganic solvents in particular, at a comparatively low fraction of, forexample, less than 30 wt %, preferably less than 20 wt %. Preferredranges are from 10 to 30 wt %, more particularly 10 to 20 wt %.

Another advantage of the basecoat material of the invention is that itcan be prepared without the use of eco-unfriendly and health-injuriousorganic solvents such as N-methyl-2-pyrrolidone, dimethylformamide,dioxane, tetrahydrofuran, and N-ethyl-2-pyrrolidone. Accordingly, thebasecoat material preferably contains less than 10 wt %, preferably lessthan 5 wt %, more preferably less than 2.5 wt % of organic solventsselected from the group consisting of N-methyl-2-pyrrolidone,dimethylformamide, dioxane, tetrahydrofuran, and N-ethyl-2-pyrrolidone.The basecoat material is preferably entirely free from these organicsolvents.

The coating compositions of the invention can be produced using themixing assemblies and mixing techniques that are customary and known forthe production of basecoat materials.

The present invention likewise provides a method for producing multicoatpaint systems, in which

(1) an aqueous basecoat material is applied to a substrate,

(2) a polymer film is formed from the coating material applied in stage(1),

(3) a clearcoat material is applied to the resulting basecoat film, andthen

(4) the basecoat film is cured together with the clearcoat film,

which is characterized in that the aqueous basecoat material used instage (1) is a basecoat material of the invention.

All of the above remarks regarding the basecoat material of theinvention also apply to the method of the invention.

Said method is used to produce multicoat color paint systems, multicoateffect paint systems, and multicoat color and effect paint systems.

The aqueous basecoat material for use in accordance with the inventionis commonly applied to metallic substrates that have been pretreatedwith a cured primer-surfacer.

Where a metallic substrate is to be coated, it is preferably furthercoated with an electrocoat system before the primer-surfacer is applied.

The pigmented aqueous basecoat material of the invention may be appliedto a metallic substrate, at the film thicknesses customary within theautomobile industry, in the range, for example, of 5 to 100 micrometers,preferably 5 to 60 micrometers. It is usual in this context to employspray application methods, such as compressed air spraying, airlessspraying, high-speed rotation, electrostatic spray application (ESTA),alone or in conjunction with hot spray application, such as hot airspraying, for example.

After the pigmented aqueous basecoat material has been applied, it canbe dried by known methods. For example, (1-component) basecoatmaterials, which are preferred, can be flashed at room temperature for 1to 60 minutes and subsequently dried, preferably at optionally slightlyelevated temperatures of 30 to 90° C. Flashing and drying in the contextof the present invention mean the evaporation of organic solvents and/orwater, as a result of which the paint becomes drier but has not yetcured or not yet formed a fully crosslinked coating film.

Then a commercial clearcoat material is applied, by likewise commonmethods, the film thicknesses again being within the customary ranges,for example 5 to 100 micrometers. Preference is given to two-componentclearcoat materials.

Following application of the clearcoat material, it may be flashed offat room temperature for 1 to 60 minutes, for example, and optionallydried. The clearcoat material is then cured together with the appliedbasecoat material. In the course of these procedures, crosslinkingreactions occur, for example, to produce on a substrate a multicoatcolor and/or effect paint system of the invention. The curing ispreferably effected by thermal means, at temperatures of 60 to 200° C.

All the film thicknesses stated in the context of the present inventionshould be understood as dry film thicknesses. The film thickness is thusthat of the cured film in question. Thus, if it is stated that a coatingmaterial is applied in a particular film thickness, this should beunderstood to mean that the coating material is applied such that thestated film thickness results after the curing.

The method of the invention can thus be used to paint in particularmetallic substrates, preferably automobile bodies or components thereof.

The method of the invention can be used further for dual finishing inOEM finishing. This means that a substrate which has been coated bymeans of the method of the invention is painted for a second time,likewise by means of the method of the invention.

The invention relates further to multicoat paint systems which areproducible by the method described above. These multicoat paint systemsare to be referred to below as multicoat paint systems of the invention.

All the above remarks relating to the aqueous basecoat material of theinvention and the method of the invention also apply correspondingly tosaid multicoat paint system.

A further aspect of the invention relates to the method of theinvention, wherein said substrate from stage (1) is a multicoat paintsystem having defects. This substrate/multicoat paint system havingdefects is thus an original finish, which is to be repaired (“spotrepair”) or completely recoated (“dual coating”).

The method of the invention is accordingly also suitable for repairingdefects on multicoat paint systems. Fault sites or film defects aregenerally faults on and in the coating, usually named according to theirshape or their appearance. The skilled person is aware of a host ofpossible kinds of such film defects.

The present invention further relates to the use of the dispersion (PD)of the invention and/or of the basecoat material of the invention forimproving the performance properties of basecoat materials and/ormulticoat paint systems produced using the basecoat material. Theinvention relates more particularly to the stated use for improving theoptical properties of multicoat paint systems, more particularly thestability toward pinholes and runs, and also for improving themechanical properties, more particularly the adhesion and the stonechipresistance.

The invention is illustrated below using examples.

Examples

Methods of Determination

1. Solids Content

Unless otherwise indicated, the solids content, also referred to assolid fraction hereinafter, was determined in accordance with DIN EN ISO3251 at 130° C.; 60 min, initial mass 1.0 g. If reference is made in thecontext of the present invention to an official standard, this of coursemeans the version of the standard that was current on the filing date,or, if no current version exists at that date, then the last currentversion.

2. Isocyanate Content

The isocyanate content, also referred to below as NCO content, wasdetermined by adding an excess of a 2% strength N,N-dibutylaminesolution in xylene to a homogeneous solution of the samples inacetone/N-ethylpyrrolidone (1:1 vol %), by potentiometric back-titrationof the amine excess with 0.1 N hydrochloric acid, in a method based onDIN EN ISO 3251, DIN EN ISO 11909, and DIN EN ISO 14896. The NCO contentof the polymer, based on solids, can be calculated back via the fractionof a polymer (solids content) in solution.

3. Hydroxyl Number

The hydroxyl number was determined on the basis of R.-P. Krüger, R.Gnauck and R. Algeier, Plaste and Kautschuk, 20, 274 (1982), by means ofacetic anhydride in the presence of 4-dimethylaminopyridine as acatalyst in a tetrahydrofuran (THF)/dimethylformamide (DMF) solution atroom temperature, by fully hydrolyzing the excess of acetic anthydrideremaining after acetylation and conducting a potentiometricback-titration of the acetic acid with alcoholic potassium hydroxidesolution. Acetylation times of 60 minutes were sufficient in all casesto guarantee complete conversion.

4. Acid Number

The acid number was determined on the basis of DIN EN ISO 2114 inhomogeneous solution of tetrahydrofuran (THF)/water (9 parts by volumeof THF and 1 part by volume of distilled water) with ethanolic potassiumhydroxide solution.

5. Degree of Neutralization

The degree of neutralization of a component x was calculated from theamount of substance of the carboxylic acid groups present in thecomponent (determined via the acid number) and the amount of substanceof the neutralizing agent used.

6. Amine Equivalent Mass

The amine equivalent mass (solution) serves for determining the aminecontent of a solution, and was ascertained as follows. The sample foranalysis was dissolved at room temperature in glacial acetic acid andtitrated against 0.1N perchloric acid in glacial acetic acid in thepresence of crystal violet. The initial mass of the sample and theconsumption of perchloric acid gave the amine equivalent mass(solution), the mass of the solution of the basic amine that is neededto neutralize one mole of perchloric acid.

7. Degree of Blocking of the Primary Amino Groups

The degree of blocking of the primary amino groups was determined bymeans of IR spectrometry using a Nexus FT IR spectrometer (from Nicolet)with the aid of an IR cell (d=25 m, KBr window) at the absorptionmaximum at 3310 cm⁻¹ on the basis of concentration series of the aminesused and standardization to the absorption maximum at 1166 cm⁻¹(internal standard) at 25° C.

8. Solvent Content

The amount of an organic solvent in a mixture, as for example in anaqueous dispersion, was determined by means of gas chromatography(Agilent 7890A, 50 m silica capillary column with polyethylene glycolphase or 50 m silica capillary column with polydimethylsiloxane phase,helium carrier gas, 250° C. split injector, 40-220° C. oven temperature,flame ionization detector, 275° C. detector temperature, n-propyl glycolas internal standard).

9. Number-Average Molar Mass

The number-average molar mass (M_(n)) was determined, unless otherwiseindicated, by means of a vapor pressure osmometer 10.00 (from Knauer) onconcentration series in toluene at 50° C. with benzophenone ascalibration substance for the determination of the experimentalcalibration constant of the instrument used, by the method of E.Schröder, G. Müller, K. F. Arndt, “Leitfaden derPolymercharakterisierung” [Principles of polymer characterization],Akademie-Verlag, Berlin, pp. 47-54, 1982.

10. Average Particle Size

The average particle size (volume average) of the polyurethane-polyureaparticles present in the dispersions (PD) of the invention wasdetermined in the context of the present invention by means of photoncorrelation spectroscopy (PCS).

Employed specifically for the measurement was a Malvern Nano S90 (fromMalvern Instruments) at 25±1° C. The instrument covers a size range from3 to 3000 nm and was equipped with a 4 mW He—Ne laser at 633 nm. Thedispersions (PD) were diluted with particle-free, deionized water asdispersing medium, before being subjected to measurement in a 1 mlpolystyrene cell at suitable scattering intensity. Evaluation took placeusing a digital correlator, with the assistance of the Zetasizeranalysis software, version 6.32 (from Malvern Instruments). Measurementtook place five times, and the measurements were repeated on a second,freshly prepared sample. The standard deviation of a 5-folddetermination was ≤4%. The maximum deviation of the arithmetic mean ofthe volume average (V-average mean) of five individual measurements was±15%. The reported average particle size (volume average) is thearithmetic mean of the average particle size (volume average) of theindividual preparations. Verification was carried out using polystyrenestandards having certified particle sizes between 50 to 3000 nm.

In example D3, described later on below, the size of the particles meantthat it was not possible to perform determination using photoncorrelation spectroscopy. Instead, the volume average of the particlesize (D[4.3]) was determined by laser diffraction in accordance with ISO13220, using a Mastersizer 2000 particle size measuring instrument (fromMalvern Instruments). The instrument operates with a red light source(max. 4 mW He—Ne, 633 nm) and a blue light source (max. 0.3 mW LED, 470nm) and detects particles in the present dispersions in the range fromabout 0.1 μm to about 2000 μm. In order to set the concentration rangeappropriate for the measurement, the sample was diluted withparticle-free, deionized water as dispersing medium (refractive index:1.33), the shading of light was set at between 3% and 15%, depending oneach sample, and measurement took place in the “Hydro 2000G” dispersingunit (from Malvern Instruments). In each case, six measurements wereperformed at stirring speeds of 2000 1/min and 3000 1/min, and themeasurements were repeated on a second, freshly prepared sample. Thevolume-weighted size distribution was calculated using the MalvernInstruments Software (Version 5.60) by means of Fraunhoferapproximation. The reported volume average of the particle size (D[4.3])is the arithmetic mean of the volume average values for the individualpreparations. The particle size measuring instrument was verified usingparticle size standards in the range from 0.2 to 190 μm.

11. Gel Fraction

The gel fraction of the polyurethane-polyurea particles (microgelparticles) present in the dispersions (PD) of the invention isdetermined gravimetrically in the context of the present invention.Here, first of all, the polymer present was isolated from a sample of anaqueous dispersion (PD) (initial mass 1.0 g) by freeze-drying. Followingdetermination of the solidification temperature—the temperature afterwhich the electrical resistance of the sample shows no further changewhen the temperature is lowered further—the fully frozen sampleunderwent its main drying, customarily in the drying vacuum pressurerange between 5 mbar and 0.05 mbar, at a drying temperature lower by 10°C. than the solidification temperature. By graduated increase in thetemperature of the heated surfaces beneath the polymer to 25° C., rapidfreeze-drying of the polymers was achieved; after a drying time oftypically 12 hours, the amount of isolated polymer (solid fraction,determined by the freeze-drying) was constant and no longer underwentany change even on prolonged freeze-drying. Subsequent drying at atemperature of the surface beneath the polymer of 30° C. with theambient pressure reduced to maximum (typically between 0.05 and 0.03mbar) produced optimum drying of the polymer.

The isolated polymer was subsequently sintered in a forced air oven at130° C. for one minute and thereafter extracted for 24 hours at 25° C.in an excess of tetrahydrofuran (ratio of tetrahydrofuran to solidfraction=300:1). The insoluble fraction of the isolated polymer (gelfraction) was then separated off on a suitable frit, dried in a forcedair oven at 50° C. for 4 hours, and subsequently reweighed.

It was further ascertained that at the sintering temperature of 130° C.,with variation in the sintering times between one minute and twentyminutes, the gel fraction found for the microgel particles isindependent of sintering time. It can therefore be ruled out thatcrosslinking reactions subsequent to the isolation of the polymericsolid increase the gel fraction further.

The gel fraction determined in this way in accordance with the inventionis also called gel fraction (freeze-dried).

In parallel, a gel fraction, hereinafter also called gel fraction (130°C.), was determined gravimetrically, by isolating a polymer sample fromaqueous dispersion (initial mass 1.0 g) at 130° C. for 60 minutes(solids content). The mass of the polymer was ascertained, after whichthe polymer was extracted in an excess of tetrahydrofuran at 25° C., inanalogy to the procedure described above, for 24 hours, after which theinsoluble fraction (gel fraction) was separated off, dried, andreweighed.

12. Solubility in Water

The solubility of an organic solvent in water was determined at 20° C.as follows. The respective organic solvent and water were combined in asuitable glass vessel, mixed, and the mixture was subsequentlyequilibrated. The amounts of water and of the solvent were selected suchthat two phases separate from one another were obtained after theequilibration. After the equilibration, a sample is taken from theaqueous phase (that is, the phase containing more water than organicsolvent) using a syringe, and this sample was diluted withtetrahydrofuran in a 1/10 ratio, the fraction of the solvent beingdetermined by means of gas chromatography (for conditions see section 8.Solvent content).

If two phases do not form irrespective of the amounts of water and thesolvent, the solvent is miscible with water in any weight ratio. Thissolvent that is therefore infinitely soluble in water (acetone, forexample) is therefore at any rate not a solvent (Z.2).

Microgel Polyurethane-Polyurea Dispersions

Example D1

Preparation of an Inventive Microgel Dispersion of aPolyesterurethaneurea by Addition of Diethylenetriaminediketimine to theExcess of a Partly Neutralized, Dicyclohexylmethane4,4′-diisocyanate-Based Polyurethane Prepolymer in Methyl Ethyl Ketoneand Subsequent Crosslinking Via Terminal Primary Amino Groups FollowingDispersion in Water

A microgel dispersion of a polyesterurethaneurea was prepared asfollows:

a) Preparation of a Partly Neutralized Prepolymer Solution

In a reaction vessel equipped with stirrer, internal thermometer, refluxcondenser, and electrical heating, 559.7 parts by weight of a linearpolyester polyol and 27.2 parts by weight of dimethylolpropionic acid(from GEO Speciality Chemicals) were dissolved under nitrogen in 344.5parts by weight of methyl ethyl ketone. The linear polyester diol wasprepared beforehand from dimerized fatty acid (Pripol® 1012, fromCroda), isophthalic acid (from BP Chemicals), and hexane-1,6-diol (fromBASF SE) (weight ratio of the starting materials: dimeric fatty acid toisophthalic acid to hexane-1,6-diol=54.00:30.02:15.98), and had ahydroxyl number of 73 mg KOH/g solid fraction, an acid number of 3.5 mgKOH/g solid fraction, a calculated number-average molar mass of 1379g/mol, and a number-average molar mass as determined via vapor pressureosmometry of 1350 g/mol.

Added in succession to the resulting solution at 30° C. were 213.2 partsby weight of dicyclohexylmethane 4,4′-diisocyanate (Desmodur® W, BayerMaterialScience) with an isocyanate content of 32.0 wt %, and 3.8 partsby weight of dibutyltin dilaurate (from Merck). The mixture was thenheated to 80° C. with stirring. Stirring was continued at thistemperature until the isocyanate content of the solution was constant at1.49% by weight. Thereafter 626.2 parts by weight of methyl ethyl ketonewere added to the prepolymer, and the reaction mixture was cooled to 40°C. When 40° C. had been reached, 11.8 parts by weight of triethylamine(from BASF SE) were added dropwise over the course of two minutes, andthe mixture was stirred for a further 5 minutes.

b) Reaction of the Prepolymer with Diethylenetriaminediketimine

Then 30.2 parts by weight of a 71.9 wt % dilution ofdiethylenetriaminediketimine in methyl isobutyl ketone were mixed inover the course of one minute (ratio of prepolymer isocyanate groups todiethylenetriaminediketimine (having a secondary amino group): 5:1mol/mol, corresponding to two NCO groups per blocked primary aminogroup), and the reaction temperature rose by 1° C. briefly followingaddition to the prepolymer solution. The dilution ofdiethylenetriaminediketimine in methyl isobutyl ketone was preparedbeforehand by azeotropic removal of water of reaction in the reaction ofdiethylenetriamine (from BASF SE) with methyl isobutyl ketone in methylisobutyl ketone at 110-140° C. Adjustment to an amine equivalent mass(solution) of 124.0 g/eq was carried out by dilution with methylisobutyl ketone. Blocking of the primary amino groups of 98.5% wasdetermined by means of IR spectroscopy, on the basis of the residualabsorption at 3310 cm⁻¹.

The solids content of the polymer solution containing isocyanate groupswas found to be 45.3%.

c) Dispersion and Vacuum Distillation

After 30 minutes of stirring at 40° C., the contents of the reactor weredispersed in 1206 parts by weight of deionized water (23° C.) over thecourse of 7 minutes. Methyl ethyl ketone was distilled off from theresulting dispersion under reduced pressure at 45° C., and any losses ofsolvent and water were made up with deionized water, giving a solidscontent of 40 wt %.

A white, stable, solids-rich, low-viscosity dispersion with crosslinkedparticles was obtained, which showed no sedimentation at all even after3 months.

The characteristics of the resulting microgel dispersion were asfollows:

Solids content (130° C., 60 min, 1 g): 40.2 wt % Methyl ethyl ketonecontent (GC): 0.2 wt % Methyl isobutyl ketone content (GC): 0.1 wt %Viscosity (23° C., rotary viscometer, 15 mPa · s shear rate = 1000/s):Acid number 17.1 mg KOH/g Solids content Degree of neutralization(calculated) 49% pH (23° C.) 7.4 Particle size (photon correlation 167nm spectroscopy, volume average) Gel fraction (freeze-dried) 85.1 wt %Gel fraction (130° C.) 87.3 wt %

Example D2

Preparation of an Inventive Microgel Dispersion of aPolyesterurethaneurea by Addition ofN,N′-bis(3-aminopropyl)ethylenediaminediketimine to the Excess of aPartly Neutralized, Dicyclohexylmethane 4,4′-diisocyanate-BasedPolyurethane Prepolymer in Methyl Ethyl Ketone and SubsequentCrosslinking Via Central Primary Amino Groups Following Dispersion inWater

A microgel dispersion of a polyesterurethaneurea was prepared asfollows:

The amount of partly neutralized prepolymer solution prepared ininventive example D1 (D1, section a, 1786.4 parts by weight) wasconditioned at 40° C., and then 35.7 parts by weight of a 77.0 wt %dilution of N,N′-bis(3-aminopropyl)ethylenediaminediketimine in methylisobutyl ketone were mixed in over the course of one minute (ratio ofprepolymer isocyanate groups toN,N′-bis(3-aminopropyl)ethylenediaminediketimine (with two secondaryamino groups): 6:1 mol/mol; corresponding to two NCO groups per blockedprimary amino group), the reaction temperature rising briefly by 1° C.following addition to the prepolymer solution, with an increase in theviscosity as well. The dilution ofN,N′-bis(3-aminopropyl)ethylenediaminediketimine in methyl isobutylketone was prepared beforehand by azeotropic removal of water ofreaction in the reaction of N,N′-bis(3-aminopropyl)ethylenediamine (fromBASF SE) with methyl isobutyl ketone in methyl isobutyl ketone at110-140° C. Adjustment to an amine equivalent mass (solution) of 110.0g/eq was carried out by dilution with methyl isobutyl ketone. Blockingof the primary amino groups of 99.0% was ascertained by means of IRspectroscopy, from the residual absorption at 3310 cm⁻¹.

The solids content of the polymer solution containing isocyanate groupswas found to be 45.1%. After 30 minutes of stirring at 40° C., thecontents of the reactor were dispersed in 1214 parts by weight ofdeionized water (23° C.) over the course of 7 minutes. Methyl ethylketone was distilled off from the resulting dispersion under reducedpressure at 45° C., and any losses of solvent and water were made upwith deionized water, giving a solids content of 40 wt %.

A white, stable, solids-rich, low-viscosity dispersion with crosslinkedparticles was obtained, which showed no sedimentation at all even after3 months.

The characteristics of the resulting microgel dispersion were asfollows:

Solids content (130° C., 60 min, 1 g): 39.8 wt % Methyl ethyl ketonecontent (GC): 0.2 wt % Methyl isobutyl ketone content (GC): 0.1 wt %Viscosity (23° C., rotary viscometer, 35 mPa · s shear rate = 1000/s):Acid number 17.2 mg KOH/g Solids content Degree of neutralization(calculated) 49% pH (23° C.) 7.5 Particle size (photon correlation 172nm spectroscopy, volume average) Gel fraction (freeze-dried) 96.1 wt %Gel fraction (130° C.) 96.8 wt %

Example D3

Preparation of a Noninventive Microgel Dispersion of aPolyesterurethaneurea by Addition of Diethylenetriaminediketimine to theExcess of a Partly Neutralized, Dicyclohexylmethane4,4′-diisocyanate-Based Polyurethane Prepolymer in Acetone andSubsequent Crosslinking Via Terminal Primary Amino Groups FollowingDispersion in Water

The noninventive microgel dispersion of a polyesterurethaneurea D3 wasprepared as in the inventive example D1; the methyl ethyl ketone solventfor preparing a partly neutralized prepolymer solution was just replacedby acetone, and the reaction temperature of originally 80° C. when usingmethyl ethyl ketone was limited to 58° C. when using acetone. Stirringwas carried out at this temperature until the isocyanate content of thesolution, as in example D1, was constant at 1.49 wt %; only the reactiontime had increased. Thereafter, in analogy to example D1, the prepolymerwas diluted with acetone, cooled to 40° C., and partly neutralized, andsubsequently was reacted using the amount ofdiethylenetriaminediketimine indicated in example D1 in methyl isobutylketone (ratio of isocyanate groups of the prepolymer todiethylenetriaminediketimine (having one secondary amino group): 5:1mol/mol, corresponding to two NCO groups per blocked primary aminogroup), the solids content of the polymer solution containing isocyanategroups was found to be 45.4%; following dispersion in water, removal ofthe solvent at 35-40° C. under reduced pressure, and compensation of thewater losses with deionized water, a white, solids-rich, low-viscositydispersion with crosslinked particles was obtained.

The microgel dispersion is unstable, and formed a sediment of 3 wt % ofthe total mass of the resulting polymer within two days.

The characteristics of the resulting microgel dispersion were asfollows:

Solids content (130° C., 60 min, 1 g): 40.5 wt % Acetone content (GC):0.0 wt % Methyl isobutyl ketone content (GC): 0.1 wt % Viscosity (23°C., rotary viscometer, 13 mPa · s shear rate = 1000/s): Acid number 17.0mg KOH/g Solids content Degree of neutralization (calculated) 49% pH(23° C.) 7.4 Volume average of the particle size (D[4.3]) 9.8 μm (Laserdiffraction, Fraunhofer) Gel fraction (freeze-dried) 87.4 wt % Gelfraction (130° C.) 89.9 wt %

Example D4

Preparation of an Inventive Microgel Dispersion of aPolyesterurethaneurea by Addition of Diethylenetriaminediketimine to theExcess of a Partly Neutralized, Isophorone Diisocyanate-BasedPolyurethane Prepolymer in Methyl Ethyl Ketone and SubsequentCrosslinking Via Terminal Primary Amino Groups Following Dispersion inWater

A microgel dispersion of a polyesterurethaneurea was prepared asfollows:

a) Preparation of a Partly Neutralized Prepolymer Solution

In a reaction vessel equipped with stirrer, internal thermometer, refluxcondenser and electrical heating, 583.0 parts by weight of the linearpolyester polyol from example D1 and 28.4 parts by weight ofdimethylolpropionic acid (from GEO Speciality Chemicals) were dissolvedunder nitrogen in 344.3 parts by weight of methyl ethyl ketone.

The resulting solution was admixed at 30° C. in succession with 188.2parts by weight of isophorone diisocyanate (Basonat® I, from BASF SE)with an isocyanate content of 37.75 wt %, and with 3.8 parts by weightof dibutyltin dilaurate (from Merck). The mixture was then heated to 80°C. with stirring. Stirring was continued at this temperature until theisocyanate content of the solution was constant at 1.55 wt %. Thereafter626.0 parts by weight of methyl ethyl ketone were added to theprepolymer, and the reaction mixture was cooled to 40° C. When 40° C.had been reached, 12.3 parts by weight of triethylamine (from BASF SE)were added dropwise over the course of two minutes, and the batch wasstirred for a further 5 minutes.

b) Reaction of the Prepolymer with Diethylenetriaminediketimine

Subsequently, 31.5 parts by weight of a 71.9 wt % dilution ofdiethylenetriaminediketimine in methyl isobutyl ketone, described inexample D1, section b (amine equivalent mass (solution): 124.0 g/eq;ratio of prepolymer isocyanate groups to diethylenetriaminediketimine(with one secondary amino group): 5:1 mol/mol; corresponds to two NCOgroups per blocked primary amino group) were admixed over the course ofa minute, the reaction temperature rising briefly by 1° C. afteraddition to the prepolymer solution.

The solids content of the polymer solution containing isocyanate groupswas found to be 45.1%.

c) Dispersion and Vacuum Distillation

After 30 minutes of stirring at 40° C., the contents of the reactor weredispersed in 1205 parts by weight of deionized water (23° C.) over thecourse of 7 minutes. Methyl ethyl ketone was distilled off under reducedpressure at 45° C. from the resulting dispersion, and any losses ofsolvent and water were compensated with deionized water, to give asolids content of 40 wt %.

A white, stable, solids-rich, low-viscosity dispersion containingcrosslinked particles was obtained, and showed no sedimentationwhatsoever even after 3 months.

The characteristics of the resulting microgel dispersion were asfollows:

Solids content (130° C., 60 min, 1 g): 40.2 wt % Methyl ethyl ketonecontent (GC): 0.2 wt % Methyl isobutyl ketone content (GC): 0.0 wt %Viscosity (23° C., rotary viscometer, 19 mPa · s shear rate = 1000/s):Acid number 17.3 mg KOH/g Solids content Degree of neutralization(calculated) 49% pH (23° C.) 7.4 Particle size (photon correlation 151nm spectroscopy, volume average) Gel fraction (freeze-dried) 84.0 wt %Gel fraction (130° C.) 85.2 wt %

Example D5

Preparation of an Inventive Microgel Dispersion of aPolyesterurethaneurea by Addition of Diethylenetriaminediketimine to theExcess of a Partly Neutralized, m-Tetramethylxylene Diisocyanate-BasedPolyurethane Prepolymer in Methyl Ethyl Ketone and SubsequentCrosslinking Via Terminal Primary Amino Groups Following Dispersion inWater

A microgel dispersion of a polyesterurethaneurea was prepared asfollows:

a) Preparation of a Partly Neutralized Prepolymer Solution

In a reaction vessel equipped with stirrer, internal thermometer, refluxcondenser, and electrical heating, 570.0 parts by weight of the linearpolyester polyol from example D1 and 27.7 parts by weight ofdimethylolpropionic acid (from GEO Speciality Chemicals) were dissolvedunder nitrogen in 344.4 parts by weight of methyl ethyl ketone.

Added to the resulting solution at 30° C. in succession were 202.0 partsby weight of m-tetramethylxylene diisocyanate (TMXDI® (Meta) aliphaticisocyanate, from Cytec), with an isocyanate content of 34.40 wt %, and3.8 parts by weight of dibutyltin dilaurate (from Merck). This wasfollowed by heating to 80° C. with stirring. Stirring was continued atthis temperature until the isocyanate content of the solution wasconstant at 1.51 wt %. Thereafter 626.4 parts by weight of methyl ethylketone were added to the prepolymer and the reaction mixture was cooledto 40° C. When 40° C. had been reached, 12.0 parts by weight oftriethylamine (from BASF SE) were added dropwise over the course of twominutes and the batch was stirred for a further 5 minutes.

b) Reaction of the Prepolymer with Diethylenetriaminediketimine

Subsequently 30.8 parts by weight of a 71.9 wt % dilution, described inexample D1, section b, of diethylenetriaminediketimine in methylisobutyl ketone were mixed in over the course of a minute (amineequivalent mass (solution): 124.0 g/eq; ratio of prepolymer isocyanategroups to diethylenetriaminediketimine (having one secondary aminogroup): 5:1 mol/mol; corresponding to two NCO groups per blocked primaryamino group), the reaction temperature rising briefly by 1° C. afteraddition to the prepolymer solution.

The solids content of the polymer solution containing isocyanate groupswas found to be 45.0%.

c) Dispersion and Vacuum Distillation

After 30 minutes of stirring at 40° C., the contents of the reactor weredispersed in 1206 parts by weight of deionized water (23° C.) over thecourse of 7 minutes. Methyl ethyl ketone was distilled off from theresulting dispersion under reduced pressure at 45° C., and any losses ofsolvent and of water were made up with deionized water, giving a solidscontent of 40 wt %.

A white, stable, solids-rich, low-viscosity dispersion with crosslinkedparticles was obtained, and showed no sedimentation at all even after 3months.

The characteristics of the resulting microgel dispersion were asfollows:

Solids content (130° C., 60 min, 1 g): 39.6 wt % Methyl ethyl ketonecontent (GC): 0.3 wt % Methyl isobutyl ketone content (GC): 0.1 wt %Viscosity (23° C., rotary viscometer, 15 mPa · s shear rate = 1000/s):Acid number 17.1 mg KOH/g Solids content Degree of neutralization(calculated) 49% pH (23° C.) 7.4 Particle size (photon correlation 156nm spectroscopy, volume average) Gel fraction (freeze-dried) 83.3 wt %Gel fraction (130° C.) 83.7 wt %

Example D6

Preparation of a Noninventive Microgel Dispersion of aPolyesterurethaneurea by Addition of Diethylenetriaminediketimine to theExcess of a Partly Neutralized Dicyclohexylmethane4,4′-diisocyanate-Based Polyurethane Prepolymer in Methyl Ethyl Ketoneat Increased Solids Content and Subsequent Crosslinking Via TerminalPrimary Amino Groups Following Dispersion in Water

The noninventive microgel dispersion of a polyesterurethaneurea D6 wasprepared as in inventive example D1, except that the amount of methylethyl ketone was reduced so as to give the solution (Z) an amount of70.1% of intermediate containing isocyanate groups and having blockedprimary amino groups (Z.1); subsequently, following dispersion in water,removal of the solvent at 45° C. under reduced pressure, andcompensation of the water losses with deionized water, a white,solids-rich, low-viscosity dispersion with crosslinked particles wasobtained.

The ratio of isocyanate groups in the prepolymer todiethylenetriaminediketimine (having one secondary amino group) remainedunchanged at 5:1 mol/mol (corresponding to two NCO groups per blockedprimary amino group). The degree of neutralization (calculated) alsoremained the same.

A white, solids-rich, low-viscosity dispersion with large, crosslinkedparticles was obtained, which showed a sediment of approximately 0.2 wt% of the total mass of the polymer present after 3 months. When thedispersion was filtered, difficulties arose because of rapid clogging ofthe filters used.

The characteristics of the resulting microgel dispersion were asfollows:

Solids content (130° C., 60 min, 1 g): 39.8 wt % Methyl ethyl ketonecontent (GC): 0.2 wt % Methyl isobutyl ketone content (GC): 0.1 wt %Viscosity (23° C., rotary viscometer, 14 mPa · s shear rate = 1000/s):Acid number 17.2 mg KOH/g Solids content Degree of neutralization(calculated) 49% pH (23° C.) 7.4 Particle size (photon correlation 2860nm spectroscopy, volume average) Volume average of the particle size(D[4.3]) 3.8 μm (Laser diffraction, Fraunhofer) Gel fraction(freeze-dried) 85.9 wt % Gel fraction (130° C.) 87.9 wt %

Further Aqueous Polyurethane-Based Dispersions

Besides the prepared inventive microgel dispersions D1, D2, D4, and D5,and also the noninventive microgel dispersions D3 and D6, further,noninventive polyurethane dispersions were prepared or their preparationattempted.

Comparative Example VD1

Preparation of a Dispersion of a Polyesterurethane by Dispersion of aMethyl Ethyl Ketone Solution of a Partly Neutralized,Dicyclohexylmethane 4,4′-diisocyanate-Based Polyesterurethane

A standard polyurethane dispersion VD1 was prepared on the basis ofdicyclohexylmethane 4,4′-diisocyanate in accordance with WO 92/15405,page 15, lines 16-20.

The characteristics of the resulting polyurethane dispersion were asfollows:

Solids content (130° C., 60 min, 1 g): 27.0 wt % Methyl ethyl ketonecontent (GC): 0.2 wt % Viscosity (23° C., rotary viscometer, 135 mPa · sshear rate = 1000/s): Acid number 19.9 mg KOH/g Solids content pH (23°C.) 7.8 Particle size (photon correlation 46 nm spectroscopy, volumeaverage) Gel fraction (freeze-dried) −0.7 wt % Gel fraction (130° C.)−0.3 wt %

Comparative Example VD2

Preparation of a Dispersion of a Polyesterurethaneurea by Dispersion ofa Methyl Ethyl Ketone Solution of a Partly Neutralized,Dicyclohexylmethane 4,4′-diisocyanate-Based Polyurethane PrepolymerHaving Free Isocyanate Groups in Water (without Addition of Ketimine orFurther Amine)

The amount of partially neutralized prepolymer solution prepared ininventive example D1 (D1, section a, 1786.4 parts by weight) wasconditioned at 40° C. and dispersed in 1193 parts by weight of deionizedwater (23° C.) over the course of 7 minutes, with stirring, withoutaddition of diketimine or further amine. The methyl ethyl ketone wasdistilled from the resulting dispersion under reduced pressure at 45°C., and any losses of solvent and water were made up with deionizedwater, to give a solids content of 40 wt %.

The dispersion was subsequently conditioned at 40° C. for 24 hours, theformation of carbon dioxide being observed in the first few hours. After24 hours, further evolution of carbon dioxide was no longer found.

A white, sedimentation-stable, solids-rich, low-viscosity dispersion wasobtained, which was noncrosslinked.

The gel fraction was determined immediately after vacuum distillationand adjustment of the solids content with deionized water, and also on adispersion conditioned subsequently at 40° C. for 24 hours. Thedetermination was repeated after four weeks of conditioning at 40° C.

The characteristics of the resulting polymer dispersion were as follows:

Solids content (130° C., 60 min, 1 g): 39.6 wt % Methyl ethyl ketonecontent (GC): 0.2 wt % Viscosity (23° C., rotary viscometer, 45 mPa · sshear rate = 1000/s): Acid number 17.3 mg KOH/g Solids content Degree ofneutralization (calculated) 49% pH (23° C.) 7.6 Particle size (photoncorrelation 172 nm spectroscopy, volume average) Gel fraction(freeze-dried) −1.2 wt % Gel fraction (130° C.) 1.8 wt % Gel fraction(freeze-dried) 1.0 wt % (dispersion after 24 hours, 40° C.) Gel fraction(130° C.) 3.6 wt % (dispersion after 24 hours, 40° C.) Gel fraction(freeze-dried) 1.1 wt % (dispersion after 4 weeks, 40° C.) Gel fraction(130° C.) 2.9 wt % (dispersion after 4 weeks, 40° C.)

Comparative Example VD3

Attempted Preparation of a Microgel Dispersion of aPolyesterurethaneurea by Addition of Diethylenetriamine to the Excess ofa Partly Neutralized, Dicyclohexylmethane 4,4′-diisocyanate-BasedPolyurethane Prepolymer in Methyl Ethyl Ketone and Dispersion in Water

Admixed over the course of one minute to the amount, prepared ininventive example D1, of partially neutralized prepolymer solution (D1,section a, 1786.4 parts by weight) at 40° C. were 8.4 parts by weight ofdiethylenetriamine (from BASF SE) (ratio of prepolymer isocyanate groupsto diethylenetriamine: 5:1 mol/mol; corresponding to two NCO groups perprimary amino group), the reaction temperature rising briefly by 2° C.,and the viscosity increasing, following addition to the prepolymersolution. The solids content of the polymer solution was found to be45.0%.

Dispersion in deionized water did not occur after 30 minutes, sinceafter just 21 minutes the reaction mixture had completely gelled.

Comparative Example VD4

Preparation of a Dispersion of a Polyesterurethaneurea by Addition ofEthylenediamine to the Excess of a Partially Neutralized,Dicyclohexylmethane 4,4′-diisocyanate-Containing Polyurethane Prepolymerin Methyl Ethyl Ketone and Dispersion in Water

A dispersion of a polyesterurethaneurea was prepared as follows:

The amount, prepared in inventive example D1, of partially neutralizedprepolymer solution (D1, section a, 1786.4 parts by weight) wasconditioned at 40° C. and then 6.1 parts by weight of ethylenediamine(from BASF SE) were admixed over the course of one minute (ratio ofprepolymer isocyanate groups to ethylenediamine (without secondary aminogroups): 4:1 mol/mol; corresponding to two NCO groups per primary aminogroup), the reaction temperature rising briefly by 1° C. after additionto the prepolymer solution. The solids content of the polymer solutionwas found to be 45.3%.

After 30 minutes of stirring at 40° C., the contents of the reactor weredivided, and one half was dispersed in 601 parts by weight of deionizedwater (23° C.) over the course of 7 minutes. The other half remained inthe reactor and was stirred at 40° C. for 12 hours more, without anygelling of the reaction mixture occurring.

From the resulting dispersion, the methyl ethyl ketone was distilled offunder reduced pressure at 45° C., and any losses of solvent and waterwere made up with deionized water, to give a solids content of 40 wt %.

A white, stable, solids-rich, low-viscosity dispersion withnoncrosslinked particles was obtained, which therefore had no microgelparticles.

The characteristics of the resulting dispersion were as follows:

Solids content (130° C., 60 min, 1 g): 39.9 wt % Methyl ethyl ketonecontent (GC): 0.2 wt % Viscosity (23° C., rotary viscometer, 55 mPa · sshear rate = 1000/s): Acid number 17.2 mg KOH/g Solids content Degree ofneutralization (calculated) 49% pH (23° C.) 7.4 Particle size (photoncorrelation 157 nm spectroscopy, volume average) Gel fraction(freeze-dried) −0.3 wt % Gel fraction (130° C.) −1.1 wt %

Evaluation of the Polymer Dispersions for Use in Silver-Blue WaterborneBasecoat Materials, and Preparation of Further Polymer Dispersions

For the application comparison, a polyurethane dispersion VD1,containing no crosslinked particles, was prepared, this polyurethanedispersion being widespread in waterborne basecoat materials (accordingto WO 92/15405, page 15, lines 16-20).

Likewise prepared for purposes of comparison was a solids-richpolyurethaneurea dispersion VD4, which formed following addition ofethylenediamine to the prepolymer after dispersion in water butcontained no microgels. It was therefore possible to show that the chainextension by means of ethylenediamine, in spite of a high isocyanateexcess, was not suitable for providing crosslinked particles.

The preparation of a waterborne basecoat material with the dispersionVD2 prepared for purposes of comparison, said dispersion having beengenerated directly in water after dispersion of the prepolymercontaining isocyanate groups, was not carried out, since, despite theobservation that a finely divided, stable dispersion is formed afterdispersion and reaction of the free isocyanate groups with water, withvigorous evolution of CO₂, this procedure nevertheless proved,surprisingly, not to be suitable for producing a microgel dispersion.Following determination of the gel fraction, crosslinked particles werefound only to a very small extent, if at all.

The reaction of the prepolymer solution with nonblockeddiethylenetriamine did indeed lead to the complete gelling of theorganic resin solution within a short time, in comparative example VD3,in spite of high dilution, even before the desired dispersion in water;however, it was not possible to prepare a microgel dispersion in thisway.

Microgel dispersions having high gel fractions were obtained in theinventive experiments D1, D2, D4, and D5 and also in the noninventiveexperiments D3 and D6.

When the solvent (Z.2) (presently methyl ethyl ketone) was replaced by adifferent solvent (presently acetone) during the preparation of aprepolymer (Z.1.1) or a composition (Z), a microgel dispersion D3 wasprepared which contained particles that were much too large. In view ofthe stability problems as a consequence of the large microgel particles,a waterborne basecoat material was not prepared. The storage stabilityof such systems is inadequate.

In preparation example D6 as well, a microgel dispersion was obtained.However, the particle size of the resulting microgel particles, with arelatively high amount of the intermediate (Z.1) in the composition (Z),prior to dispersing (70.1% relative to 45.3% in preparation example D1),was significantly increased, and this adversely affected the long-termstability of the dispersion. Once again, because of the poor storagestability, the preparation of basecoat materials and their subsequentapplication were not carried out.

For the further analysis of the influence of the fraction of theintermediate (Z.1) in the composition (Z), further microgel dispersionswere prepared. In this case, starting from the preparation of dispersionD1, only the fraction of the intermediate (Z.1) in the composition (Z)was varied in each case.

Table I. shows the microgel dispersions prepared, particularized inrelation to the particle size. Dispersions D1 and D6 are likewiselisted. For greater ease of comprehension, dispersion D1 is listed asdispersion Df, and dispersion D6 as dispersion Dk. All dispersionscontained polymer particles with a gel fraction of more than 80%.

TABLE I Average particle size in nm Dispersion Fraction of (Z.1) in (Z)in wt % (determined via PCS) Da 20.1 1360 Db 30.0 394 Dc 35.0 266 Dd40.0 155 De 42.5 162 Df (=D1) 45.3 167 Dg 47.5 158 Dh 50.0 155 Di 55.2970 Dj 60.0 1645 Dk (=D6) 70.1 2860/3800¹ ¹The value of 3800 nm wasmeasured by means of laser diffraction.

The results show that the fraction of the intermediate (Z.1) in thecomposition (Z) and hence also the solids content of this compositionmust, surprisingly, not be too high, so as to give microgel dispersionsin which the polyurethane-polyurea particles present have averageparticle sizes within the acceptable range. Likewise surprisingly, theaverage particle sizes become larger again even when the fractions ofthe intermediate become very small. However, at fractions of theintermediate which are too small, and hence at high fractions of organicsolvents, there is no longer any further benefit anyway, owing to theenvironmental and economic disadvantages.

Overall it is found that fractions of the intermediate that becomerelatively high and also fractions of the intermediate that become verylow are accompanied by a rapid increase in the average particle sizes ofthe polyurethane-polyurea particles.

Preparation of Silver-Blue Waterborne Basecoat Materials

For the application comparison, a polyurethane dispersion VD1 (accordingto WO 92/15405, page 15, lines 16-20) was used to prepare a standardwaterborne basecoat material BL-V1, which, in contrast to allinventively prepared waterborne basecoat materials, was equipped with aphyllosilicate thickener, as also in patent application WO 92/15405, inorder to prevent vertical running from the metal panel duringapplication and drying.

A phyllosilicate-free waterborne basecoat material was likewise preparedfor comparison purposes, on the basis of a high-solids polyurethaneureadispersion VD4, which formed following addition of ethylenediamine tothe prepolymer after dispersion in water, but which contained nomicrogels.

Waterborne basecoat materials (BL-A1 to BL-A4) were prepared from theinventively prepared microgel dispersions D1, D2, D4, and D5, thesebasecoat materials, in contrast to the standard waterborne basecoatmaterial BI-V1, being free from phyllosilicate thickeners.

The preparation of the waterborne basecoat materials is described indetail hereinafter.

Preparation of a Silver-Blue Waterborne Basecoat Material BL-V1 asComparative Example, Based on a Polyurethane Dispersion VD1 withPolyurethane Particles which are not Crosslinked, and Amenable to DirectApplication as a Coloring Coat onto a Cured Surfacer

The components listed under “aqueous phase” in Table 1 are stirredtogether in the prescribed order to form an aqueous mixture. In the nextstep, an organic mixture is prepared from the components listed under“organic phase”. The organic mixture is added to the aqueous mixture.The combined mixture is then stirred for 10 minutes and adjusted, usingdeionized water and N,N-dimethylethanolamine (from BASF SE), to a pH of8.1 and to a spray viscosity of 73 mPa·s under a shearing load of 1000s⁻¹, as measured with a rotary viscometer (Rheomat RM 180 instrumentfrom Mettler-Toledo) at 23° C.

TABLE 1 Preparation of a silver-blue waterborne basecoat material BL-V1Designation of the waterborne basecoat material BL-V1 Component Parts byweight AQUEOUS PHASE Aqueous solution of 3% sodium lithium magnesiumphyllosilicate 24.7 Laponite ® RD (from Altana-Byk) and 3% Pluriol ®P900 (from BASF SE) VD-1 18 Polyurethane dispersion, prepared accordingto page 15, Lines 16-20 of WO 92/15405 Hydroxy-functional polyester;prepared as per example D, column 3.2 16, lines 37-59 of DE-A-4009858Luwipal ® 052 (from BASF SE), melamine-formaldehyde resin 4.3 TMDD 50%BG (from BASF SE), 52% strength solution of 2,4,7,9- 1.9tetramethyl-5-decyne-4,7-diol in butyl glycol 10% strength solution ofN,N-dimethylethanolamine 0.8 (from BASF SE) in water Butyl glycol (fromBASF SE) 5.7 Hydroxy-functional, polyurethane-modified polyacrylate;prepared as 4.7 per page 7, line 55 to page 8, line 23 of DE 4437535 A110 wt % strength solution of Rheovis ® AS 1130 (BASF SE), 4 rheologicalagent 50 wt % strength solution of Rheovis ® PU 1250 (BASF SE), 0.47rheological agent Isopropanol (from BASF SE) 1.9 Triethylene glycol(from BASF SE) 2.4 2-Ethylhexanol (from BASF SE) 2 Isopar ® L (fromExxonMobil Chemical), solvent 1 (isoparaffinic hydrocarbon) Carbon blackpaste 4.3 Blue paste 6.9 Red paste 0.23 Interference pigment slurryIriodine 9119 Polarweiß SW (from Merck), a silver-white 1 interferencepigment; mica, coated with rutile (TiO₂) Iriodin ® 9225 SQB RutilPerlblau SW (from Merck), 0.06 a blue interference pigment; mica, coatedwith rutile (TiO₂) Mixing varnish, prepared as per column 11, lines 1-173.2 of EP 1534792-B1 Deionized water 7.98 ORGANIC PHASE Mixture of twocommercial aluminum pigments STAPA Hydrolux 0.36 1071 aluminum and STAPAHydrolux VP No. 56450/G aluminum (from Eckart Effect Pigments) Butylglycol (from BASF SE) 0.5 Hydroxy-functional polyester; prepared as perexample D, column 0.3 16, lines 37-59 of DE-A-4009858 10% strengthsolution of N,N-dimethylethanolamine 0.1 (from BASF SE) in water (forthe adjustment of pH and spray viscosity)

Production of the Carbon Black Paste

The carbon black paste was produced from 57 parts by weight of anacrylated polyurethane dispersion prepared as per international patentapplication WO 91/15528 binder dispersion A, 10 parts by weight ofMonarch® 1400 carbon black, 6 parts by weight of dimethylethanolamine(10% strength in DI water), 2 parts by weight of a commercial polyether(Pluriol® P900 from BASF SE), and 25 parts by weight of deionized water.

Production of the Blue Paste

The blue paste was produced from 59 parts by weight of an acrylatedpolyurethane dispersion prepared as per international patent applicationWO 91/15528 binder dispersion A, 25 parts by weight of Palomar Blue®15:1, 1.3 parts by weight of dimethylethanolamine (10% strength in DIwater), 0.25 part by weight of Parmetol® N 20, 4 parts by weight of acommercial polyether (Pluriol® P900 from BASF SE), 2 parts by weight ofbutyl glycol, and 10.45 parts by weight of deionized water.

Production of the Red Paste

The red paste was produced from 38.4 parts by weight of an acrylatedpolyurethane dispersion prepared as per international patent applicationWO 91/15528 binder dispersion A, 47.1 parts by weight of Bayferrox® 13BM/P, 0.6 part by weight of dimethylethanolamine (10% strength in DIwater), 4.7 parts by weight of a commercial polyether (Pluriol® P900from BASF SE), 2 parts by weight of butyl glycol, and 7.2 parts byweight of deionized water.

Preparation of Inventive, Silver-Blue Waterborne Basecoat Materialswhich Contain Polyurethaneurea Microgels (BL-A1 to BL-A4) and which canbe Applied Directly as a Coloring Coat to a Cured Surfacer; andPreparation, as Comparative Example, of a Silver-Blue WaterborneBasecoat Material with Polyurethaneurea Particles which are notCrosslinked (BL-V2)

The components listed under “aqueous phase” in Table 2 are stirredtogether in the order stated to form an aqueous mixture. In the nextstep an organic mixture is prepared from the components listed under“organic phase”. The organic mixture is added to the aqueous mixture.The combined mixture is then stirred for 10 minutes and adjusted, usingdeionized water and N,N-dimethylethanolamine (from BASF SE), to a pH of8.1 and to a spray viscosity of 80±5 mPa·s under a shearing load of 1000s⁻¹, as measured with a rotary viscometer (Rheomat RM 180 instrumentfrom Mettler-Toledo) at 23° C.

TABLE 2 Preparation of silver-blue waterborne basecoat materials BL-A1to BL-A4 and BL-B2 Designation of the waterborne basecoat material BL-A1BL-A2 BL-A3 BL-A4 BL-V2 Component Parts by weight AQUEOUS PHASE Butylglycol 2.000 2.000 2.000 2.000 2.000 Hydroxy-functional 3.200 3.2003.200 3.200 3.200 polyester, prepared as per example D, page 10 of DE4009858 C2, Luwipal ® 052 (from BASF 4.300 4.300 4.300 4.300 4.300 SE),Melamine-formaldehyde resin 10% strength solution of 0.600 0.600 0.6000.600 0.600 N,N-dimethylethanolamine (from BASF SE) in waterHydroxy-functional, 4.700 4.700 4.700 4.700 4.700 polyurethane-modifiedpolyacrylate, prepared as per example D, pages 7-8 of DE 4437535 A1, PUmicrogel dispersion as 12.400 per preparation example D1 PU microgeldispersion as 12.525 per preparation example D2 PU microgel dispersionas 12.400 per preparation example D4 PU microgel dispersion as 12.588per preparation example D5 PU dispersion as per 12.493 preparationexample VD4 Butyl glycol 2.000 2.000 2.000 2.000 2.000 Adekanol ®UH-756VF 0.150 0.150 0.150 0.150 0.150 (from Adeka), a polyurethaneassociative thickener Deionized water 1.000 1.000 1.000 1.000 1.000Carbon black paste 4.300 4.300 4.300 4.300 4.300 Blue paste 6.900 6.9006.900 6.900 6.900 Red paste 0.230 0.230 0.230 0.230 0.230 Deionizedwater 1.000 1.000 1.000 1.000 1.000 Tris(2- 3.000 3.000 3.000 3.0003.000 butoxyethyl)phosphate (from Solvay) Deionized water 9.000 9.0009.000 9.000 9.000 Interference pigment suspension PU microgel dispersion2.200 as per preparation example D1 PU microgel dispersion 2.222 as perpreparation example D2 PU microgel dispersion 2.200 as per preparationexample D4 PU microgel dispersion 2.233 as per preparation example D5 PUdispersion as per 2.217 preparation example VD4 Iriodin ® 9119 Polarweiß1.000 1.000 1.000 1.000 1.000 SW (from Merck), a silver-whiteinterference pigment; mica, coated with rutile (TiO₂) Iriodin ® 9225 SQBRutil 0.060 0.060 0.060 0.060 0.060 Perlblau SW (from Merck), a blueinterference pigment; mica, coated with rutile (TiO₂) ORGANIC PHASEButyl glycol 0.360 0.360 0.360 0.360 0.360 Commercial aluminum 0.3600.360 0.360 0.360 0.360 pigment STAPA Hydrolux 200 (from Eckart EffectPigments) in a solvent mixture composed of hydrogen- treated naphtha,light aromatic solvent naphtha (petroleum), and butyl glycolHydroxy-functional 0.360 0.360 0.360 0.360 0.360 polyester, prepared asper example D, page 10 of DE 4009858 C2 10% strength solution of 0.0180.018 0.018 0.018 0.018 N,N-dimethylethanolamine (from BASF SE) in water(for the adjustment of pH and spray viscosity)

The preparation of the red, blue, and carbon black pastes used hasalready been described under Table 1.

Comparison Between Inventive Waterborne Basecoat Materials BL-A1 toBL-A4 with the Waterborne Basecoat Materials BL-V1 and BL-V2 in Respectof Solids Content, Volume Solids, pH, and Viscosity

First of all, solids content, volume solids, pH, and viscosity of theinventively prepared waterborne basecoat materials BL-A1 to BL-A4without phyllosilicate thickener were contrasted with the standardwaterborne basecoat material BL-V1, which contained a phyllosilicatethickener. As a second comparison, the waterborne basecoat materialBL-V2, containing the polyurethane-urea dispersion VD4, was employed,which was likewise free from phyllosilicate thickener but which, likecomparative waterborne basecoat material BL-V1, and in contrast to theinventively prepared waterborne basecoat materials, contained noinventive dispersion (PD). The results are shown in Table 3.

TABLE 3 Characterization of the comparative waterborne basecoatmaterials BL-V1 and BL-V2 and of the inventive waterborne basecoatmaterials BL-A1 to BL-A4 in respect of solids content, volume solids, pHand viscosity Comparative Inventive Waterborne basecoat material BL-V1BL-V2 BL-A1 BL-A2 BL-A3 BL-A4 Polymer dispersion VD1 VD4 D1 D2 D4 D5Solids content 17.1 37.6 36.0 35.8 35.4 37.8 in % Volume solids ¹⁾ 14.233.9 32.6 32.3 32.0 34.0 in % pH (original, 8.1 8.1 8.1 8.1 8.1 8.1 23°C.) Viscosity in mPa · s at 1000 s⁻¹ 73 83 81 80 82 82 at 1 s⁻¹ 3100 4004300 4600 3900 2100 Contains Yes No No No No No Laponite ® RD thickenersolution²⁾ ¹⁾ Volume solids (calculated): The volume solids wascalculated according to VdL-RL 08 [German Paint Industrial AssociationGuideline], “Determining the solids volume of anticorrosion coatingmaterials as basis for productivity calculations”, Verband derLackindustrie e.V., Dec. 1999 version. The volume solids VSC (solidsvolume) was calculated according to the following formula, incorporatingthe physical properties of the relevant materials used (density of thesolvents, density of the solids): VSC = (density (wet coating) × solidfraction (wet coating))/density (baked coating) VSC volume solidscontent in % Density (wet coating): calculated density of the wetcoating material from the density of the individual components (densityof solvents and density of solids) in g/cm³ Solid fraction (wetcoating): solids content (in %) of the wet coating material according toDIN EN ISO 3251 at 130° C., 60 min, initial mass 1.0 g. Density (bakedcoating): density of the baked coating material on the metal panel ing/cm³ ²⁾Laponite ® RD - thickener solution: Aqueous solution of 3%sodium lithium magnesium phyllosilicate Laponite ® RD (from Altana-Byk)and 3% Pluriol ® P900 (from BASF SE)

The results in Table 3 show that the inventive basecoat materialscombine excellent rheological behavior with a very high solids content.While the viscosity under high shearing load is within the range correctfor spray application, in other words a fairly low range (sprayviscosity), the viscosity under low shearing load (representative forthe coating material following application on the substrate) issignificantly higher, providing an appropriate stability with respect inparticular to runs. While the basecoat material BL-V1 has acorrespondingly advantageous rheological profile, but exhibits distinctdisadvantages in terms of solids content, the basecoat material BL-V2does not possess any acceptable rheological behavior (much too low aviscosity under low shearing load).

Comparative Experiments Between the Inventive Waterborne BasecoatMaterials BL-A1 to BL-A4 with the Waterborne Basecoat Materials BL-V1and BL-V2 in Respect of Run Stability and Popping Stability, PinholingLimit, and Number of Pinholes

For the determination of the running limit, popping limit, and pinholinglimit and the number of pinholes, multicoat paint systems were producedusing the waterborne basecoat materials (BL-V1, BL-V2 and also BL-A1 toBL-A4). The multicoat paint systems were produced using the waterbornebasecoat materials, according to the following general protocol:

A steel panel of dimensions 30 cm×50 cm coated with a cured surfacersystem was provided with an adhesive strip on one longitudinal edge, inorder to be able to determine the film thickness differences aftercoating. The waterborne basecoat material was applied electrostaticallyin wedge format. The resulting waterborne basecoat film was flashed offat room temperature for one minute and subsequently dried in an aircirculation oven at 70° C. for 10 minutes. Applied atop the driedwaterborne basecoat film was a ProGloss® two-component clearcoatmaterial available commercially from BASF Coatings GmbH (FF99-0345). Theresulting clearcoat film was flashed off at room temperature for 20minutes. Waterborne basecoat film and clearcoat film were then jointlycured in an air circulation oven at 140° C. for 20 minutes. The filmthickness of the cured clearcoat film was constant over the whole panel(±1 μm), with a clearcoat film thickness of 35 to 45 μm.

In the case of the determination of the popping limit, pinholing limitand number of pinholes, the panels were dried horizontally in an aircirculation oven and cured, and the popping limit and pinholing limitwere determined visually, by ascertaining the resulting film thicknessof the basecoat film, increasing in wedge format, at which pops andpinholes, respectively, first occurred. In the case of the number ofpinholes, furthermore, a determination was made of the number ofpinholes which occurred on the coated metal panel with the edge length30 cm×50 cm.

In the case of the determination of the running limit, perforated metalpanels with the same dimensions, made from steel, were used; the panelswere coated as described above, and the applied coating materials weredried and cured as described above, except that the panels were placedvertically in the oven in each case after application of waterbornebasecoat material and application of clearcoat material.

The film thickness from which runs occur is termed the running limit,and was ascertained visually.

Table 4 provides an overview of the results of the determination ofrunning limit, popping limit, pinholing limit, and number of pinholes:

Whereas waterborne basecoat material BL-V1 contained a Laponite® RDphyllosilicate thickener, all of the other waterborne basecoat materialswere free from this thickener component.

While the comparative waterborne basecoat materials BL-V1 and BL-V2 hadno crosslinked particles, the inventively prepared waterborne basecoatmaterials BL-A1 to BL-A4 contained inventive dispersions (PD).

TABLE 4 Results of the determination of running limit, popping limit,pinholing limit, and number of pinholes for multicoat paint systemsbased on the waterborne basecoat materials BL-A1 to BL-A4 and BL-B1 toBL-B2 Comparative Inventive Waterborne basecoat material BL-V1 BL-V2BL-A1 BL-A2 BL-A3 BL-A4 Polyurethane dispersion VD1 VD4 D1 D2 D4 D5Contains Yes No No No No No Laponite ® RD thickener solution¹⁾ Runninglimit in 23 8 >60 >60 >60 >60 μm ²⁾ Popping limit in 12 14 39 40 35 31μm ³⁾ Pinholing limit in 16 13 36 36 36 30 μm ⁴⁾ Number of 17 >100 12 1514 20 pinholes ⁵⁾ ¹⁾ Laponite ® RD thickener solution: Aqueous solutionof 3% sodium lithium magnesium phyllosilicate Laponite ® RD (fromAltana-Byk) and 3% Pluriol ® P900 (from BASF SE) ²⁾ Running limit in μm:Film thickness from which runs occur ³⁾ Popping limit in μm: Filmthickness from which runs occur ⁴⁾ Pinholing limit in μm: Film thicknessof the basecoat film from which pinholes occur following application ofa wedge of basecoat material and a constant layer of a two-componentclearcoat material, with joint curing in an air circulation oven at 140°C., 20 minutes ⁵⁾ Number of pinholes: Number of pinholes from pinholinglimit of the coated metal panel with edge length 30 cm × 50 cm

The results show that the use of the inventive dispersions (PD) in thewaterborne basecoat materials BL-A1 to BL-A4 for producing multicoatpaint systems, in comparison to the use of the waterborne basecoatmaterials BL-V1 and BL-V2, exhibits distinct advantages in respect ofall the optical properties evaluated.

Comparative Experiments Between the Inventive Waterborne BasecoatMaterials BL-A1 to BL-A4 with the Waterborne Basecoat Materials BL-V1and BL-V2 in Relation to Adhesion Properties on the Basis of Cross-Cutand Stonechip Results

For the determination of the adhesion properties, multicoat paintsystems were produced with the comparative waterborne basecoat materialsBL-V1 and BL-V2 and with the inventive waterborne basecoat materialsBL-A1 to BL-A4 in accordance with the following general protocol:

Original Finish

The substrate used was a metal panel with dimensions of 10 cm×20 cm,which had a cured surfacer system produced from a commercial surfacer,with a film thickness of 30±3 μm. In the production of this substrate,the surfacer was subjected to intermediate drying at 80° C. over aperiod of 10 minutes and then baked at 150° C./14 minutes oralternatively at 190° C./30 minutes. In each case, to these differentlybaked substrates, the waterborne basecoat material was initially appliedpneumatically with a target film thickness of 14±2 μm. After thewaterborne basecoat material had been flashed off at room temperaturefor 1 min, it was subjected to intermediate drying in an air circulationoven at 70° C. for 10 minutes. Then the ProGloss® two-componentclearcoat material available commercially from BASF Coatings GmbH(FF99-0345) was applied, likewise pneumatically, with a target filmthickness of 40±5 μm, and, after flashing off for 20 minutes at roomtemperature, basecoat and clearcoat were baked jointly at 125° C./20minutes (underbaked original finish) or alternatively at 160° C./30minutes (overbaked original finish) in an air circulation oven. Thisgave multicoat paint systems produced according to production conditions1 or 2 (see Table 5.1).

Refinish

Over the original finish (overbaked and underbaked), after cooling toroom temperature, first of all the waterborne basecoat material wasapplied pneumatically again, with a target film thickness of 14±2 μm,and, after 1 minute of flashing off at room temperature, the waterbornebasecoat material was subjected to intermediate drying in an aircirculation oven at 70° C. for 10 minutes. Then the ProGloss®two-component clearcoat material available commercially from BASFCoatings GmbH (FF99-0345) was applied, likewise pneumatically, with atarget film thickness of 40±5 μm, and, after flashing off for 20 minutesat room temperature, basecoat and clearcoat were baked jointly at 125°C./20 minutes (underbaked refinish) or alternatively at 160° C./30minutes (overbaked refinish) in an air circulation oven.

This gave in each case an overbaked or underbaked dual finish, which isreferred to below as overbaked or underbaked refinish or else asmulticoat paint systems produced according to production conditions 3and 4 (see Table 5.1).

Table 5.1 again brings together the differences between the individualmulticoat systems in terms of the production conditions, especiallybaking conditions.

TABLE 5.1 Production conditions for the multicoat systems on metalpanels 1 to 4 Multicoat system Pro- Basecoat Basecoat duction material/material/ condi- Clearcoat Clearcoat tions Surfacer material material 1Original 150° C. 14 min 125° C. 20 min finish (under- baked) 2 Original190° C. 30 min 160° C. 30 min finish (over- baked) 3 Refinish 150° C. 14min 125° C. 20 min 125° C. 20 min (under- baked) 4 Refinish 190° C. 30min 160° C. 30 min 160° C. 30 min (over- baked)

To assess the adhesion properties of these multicoat paint systems, theywere subjected to the cross-cut and stonechip tests.

The cross-cut test was carried out according to DIN 2409 on unexposedsamples. The results of the cross-cut test were assessed according toDIN EN ISO 2409 (rating 0 to 5; 0=best score, 5=worst score).

The stonechip test was carried out according to DIN EN ISO 20567-1,method B. The results of the stonechip test were assessed according toDIN EN ISO 20567-1 (values ≤1.5 satisfactory, values >1.5unsatisfactory).

In Table 5.2, the results of the cross-cut and stonechip tests have beencompiled.

TABLE 5.2 Results of cross-cut and stonechip test on underbaked andoverbaked original finishes refinishes of the waterborne basecoatmaterials BL-V1 and BL-V2 in comparison to inventive waterborne basecoatmaterials BL-A1 to BL-A4 Comparative Inventive Waterborne basecoatmaterial BL- BL- BL- BL- BL- BL- Pro- V1 V2 A1 A2 A3 A4 ductionPolyurethane dispersion con- VD4 ditions Testing VD1 *) D1 D2 D4 D5 1Cross-cut 0 Not 0 0 0 0 (rating) ¹⁾ coatable 1 Stonechip test 1.0 due to1.5 1.0 1.5 1.5 (rating) ²⁾ runs 2 Cross-cut 0 forming 0 0 1 0 (rating)¹⁾ 2 Stonechip test 1.5 1.5 1.5 1.5 1.5 (rating) ²⁾ 3 Cross-cut 0 0 0 00 (rating) ¹⁾ 3 Stonechip test 1.5 1.5 1.0 1.5 1.5 (rating) ²⁾ 4Cross-cut 1 0 0 1 0 (rating) ¹⁾ 4 Stonechip test 1.5 1.5 1.5 1.5 1.5(rating) ²⁾ *) The comparative basecoat material BL-V2 was uncoatableowing to formation of runs. ¹⁾ Cross-cut test: The cross-cut test wascarried out according to DIN 2409 on unexposed samples. The results ofthe cross-cut test were assessed according to DIN EN ISO 2409. (Rating 0to 5; 0 = best score, 5 = worst score): Cross-cut ≤1: SatisfactoryCross-cut >1: Unsatisfactory ²⁾ Stonechip test on underbaked andoverbaked original finishes and refinishes (see Table 5.1). For thispurpose, the stonechip test of DIN EN ISO 20567-1, method B, was carriedout. The results of the stonechip test were assessed according to DIN ENISO 20567-1: Stonechipping ≤1.5: Satisfactory Stonechipping >1.5:Unsatisfactory

The results confirm that the use of inventive polyurethane-polyureamicrogel dispersions in waterborne basecoat materials withoutphyllosilicate thickeners does not carry any adhesion problems. Instead,a level of adhesion is achieved that is of comparable quality to, and insome cases even an improvement on, that of multicoat paint systemsproduced using the standard waterborne basecoat material BL-V1 withphyllosilicate thickener.

Comparison of the Inventive Silver-Blue Waterborne Basecoat MaterialsBL-A1 and BL-A2 with the Standard Waterborne Basecoat Material BL-V1Containing Phyllosilicate Thickener, Applied Directly as Coloring Coatto a Cured Surfacer, in Respect of Angle-Dependent Hue Values

For the determination of the angle-dependent hue values resulting fromthe various waterborne basecoat materials, multicoat paint systems wereproduced according to the following general protocol:

A steel panel with dimensions of 10×20 cm, coated with a standardcathodic electrocoat (Cathoguard® 500 from BASF Coatings GmbH), wascoated with a standard surfacer (SecuBloc medium gray from BASF CoatingsGmbH) with a target film thickness of 25-35 μm. After flashing off atroom temperature for 10 minutes and also after intermediate drying ofthe aqueous surfacer over a period of 10 minutes at 70° C., it was bakedat a temperature of 160° C. over a period of 30 minutes.

The waterborne basecoat materials BL-A1, BL-A2 and BL-V1 were applied bydual application to the steel panels coated as described above.Application in the first step was electrostatic with a target filmthickness of 8-11 μm; in the second step, after a flash-off time of 3minutes and 40 seconds at room temperature, coating took placepneumatically with a target film thickness of 3-5 μm. Subsequently,after a further flash-off time of 4 minutes and 30 seconds at roomtemperature, the resulting waterborne basecoat film was dried in an aircirculation oven at 70° C. for 5 minutes.

Applied atop the dried waterborne basecoat film was a ProGloss®two-component clearcoat material available commercially from BASFCoatings GmbH (FF99-0345). The resulting clearcoat film was flashed offat room temperature for 20 minutes. Waterborne basecoat film andclearcoat film were then jointly cured in an air circulation oven at140° C. for 20 minutes.

The film thickness of the cured clearcoat film was constant over theentire panel (±1 μm) with a clearcoat film thickness of 40 to 45 μm.

The multicoat paint systems obtained accordingly were measured using anX-Rite spectrophotometer (X-Rite MA68 Multi-Angle Spectrophotometer).The surface is illuminated with a light source, and spectral detectionin the visible range is carried out at different angles.

The spectral measurements obtained in this way can be used, taking intoaccount the standardized spectral values and also the reflectionspectrum of the light source used, to calculate color values in the CIEL*a*b* color space, where L* characterizes the lightness, a* thered-green value, and b* the yellow-blue value. This method is described,for materials comprising metal flakes, in ASTM E2194-12.

Table 6 reports the respective hue values for the various coatingmaterials, utilizing the values of BL-V1 as reference. The valuesreported are CIE L*a*b* values.

TABLE 6 Color values of multicoat paint systems produced using thestandard waterborne basecoat material BL-V1 (reference) and thewaterborne basecoat materials BL-A1 and BL-A2. Waterborne basecoatmaterial BL-V1 BL-A1 BL-A2 Inventive No Yes Yes Laponite ® RD Yes No NoPolyurethane microgel No Yes Yes Color Measurement values¹⁾ angle ΔL*15° 0 −0.27 −0.41 25° 0 −0.12 −0.19 45° 0 0.07 −0.01 75° 0 0.25 0.10110°  0 0.31 0.27 Δa* 15° 0 −0.02 0.10 25° 0 0.00 0.06 45° 0 0.00 0.0575° 0 0.07 0.09 110°  0 −0.13 0.08 Δb* 15° 0 0.07 0.07 25° 0 0.00 0.0045° 0 −0.02 −0.03 75° 0 −0.07 0.08 110°  0 −0.06 0.10 ¹⁾Angle-dependentcolor values in the CIE L*a*b* color space: L* = lightness ΔL* = colordifference − difference between L* of the standard and L* of the articleunder test a* = red-green value Δa* = color difference − differencebetween a* of the standard and a* of the article under test b* =yellow-blue value Δb* = color difference − color difference between b*of the standard and b* of the article under test A description is givenof the method in ASTM E2194-12 for materials comprising metal flake

The hue values of the inventive waterborne basecoat materials arevirtually identical with those of the standard waterborne basecoatmaterial; the deviations reside in fluctuation ranges arising duringcoating operations. All multicoat paint systems have a similar visualappearance and were free from any defects.

1: An aqueous polyurethane-polyurea dispersion comprisingpolyurethane-polyurea particles present in the dispersion, having anaverage particle size of 40 to 2000 nm and having a gel fraction of atleast 50%, wherein the dispersion is obtained by dispersing, in anaqueous phase, a composition comprising, based in each case on the totalamount of the composition, 15 to 65 wt % of at least one intermediatecomprising isocyanate groups and blocked primary amino groups, and 35 to85 wt % of at least one organic solvent which has a solubility in waterof not more than 38 wt % at a temperature of 20° C., thereby obtaining adispersion, and at least partly removing the at least one organicsolvent from the dispersion, wherein the at least one intermediate isprepared by a process comprising a reaction of at least one polyurethaneprepolymer containing isocyanate groups and comprising anionic groupsand/or groups which can be converted into anionic groups, with at leastone polyamine comprising at least two blocked primary amino groups andat least one free secondary amino group, by addition reaction ofisocyanate groups from the at least one polyurethane prepolymer withfree secondary amino groups from the at least one polyamine. 2: Theaqueous polyurethane-polyurea dispersion as claimed in claim 1, whereinthe at least one polyurethane prepolymer comprises carboxylic acidgroups. 3: The aqueous polyurethane-polyurea dispersion as claimed inclaim 1, wherein the blocked primary amino groups of the at least onepolyamine are blocked with ketones. 4: The aqueous polyurethane-polyureadispersion as claimed in claim 1, wherein the at least one polyaminecomprises one or two free secondary amino groups and two blocked primaryamino groups. 5: The aqueous polyurethane-polyurea dispersion as claimedin claim 4, wherein the at least one polyamine consists of one or twofree secondary amino groups, two blocked primary amino groups, andaliphatically saturated hydrocarbon groups. 6: The aqueouspolyurethane-polyurea dispersion as claimed in claim 1, wherein, in thereaction of the at least one prepolymer with the at least one polyamine,the molar amounts of isocyanate groups from the at least one prepolymerand amino groups from the at least one polyamine satisfy a condition [n(isocyanate groups from the at least one prepolymer)−n (free secondaryamino groups from the at least one polyamine)]/n (blocked primary aminogroups from the at least one polyamine)=1.2/1 to 4/1. 7: The aqueouspolyurethane-polyurea dispersion as claimed in claim 1, wherein thefraction of the at least one intermediate in the composition is from 35to 52.5 wt %. 8: The aqueous polyurethane-polyurea dispersion as claimedin claim 1, wherein the at least one organic solvent is methyl ethylketone. 9: The aqueous polyurethane-polyurea dispersion as claimed inclaim 1, which comprises 25 to 55 wt % of a polyurethane-polyureapolymer of the polyurethane-polyurea particles and 45 to 75 wt % ofwater, and wherein a total fraction of polyurethane-polyurea polymer andwater is at least 90 wt %. 10: A process for preparing an aqueouspolyurethane-polyurea least 50%, said process comprising, in in thestated order: dispersing, in an aqueous phase, a composition comprising,based in each case on the total amount of the composition 15 to 65 wt %of at least one intermediate comprising at least one isocyanate groupand at least one blocked primary amino group, and 35 to 85 wt % of atleast one organic solvent which has a solubility in water of not morethan 38 wt % at a temperature of 20° C., thereby obtaining a dispersion,and at least partly removing the at least one organic solvent from thedispersion, thereby obtaining an aqueous polyurethane-polyureadispersion comprising polyurethane-polyurea particles having an averageparticle size of 40 to 2000 nm and a gel fraction of at least 50%,wherein the at least one intermediate is prepared by a processcomprising a reaction of at least one polyurethane prepolymer comprisingisocyanate groups and comprising anionic groups and/or groups which canbe converted into anionic groups, with at least one polyamine comprisingat least two blocked primary amino groups and at least one freesecondary amino group, by addition reaction of isocyanate groups fromthe at least one polyurethane prepolymer with free secondary aminogroups from the at least one polyamine. 11: A pigmented aqueous basecoatmaterial comprising the dispersion as claimed in claim
 1. 12: Thepigmented aqueous basecoat material as claimed in claim 11, which has asolids content of 30% to 50%. 13: The pigmented aqueous basecoatmaterial as claimed in claim 11, further comprising a melamine resin andat least one hydroxy-functional polymer which is different from thepolymer present in the dispersion. 14: A method for producing amulticoat paint system, the method comprising: (1) applying the aqueousbasecoat material of claim 11 to a substrate, thereby obtaining acoating material, (2) forming a polymer film from the coating material,thereby obtaining a basecoat film, (3) applying a clearcoat material tothe basecoat film, thereby obtaining a clearcoat film on the basecoatfilm, and then (4) curing the basecoat film is cured together with theclearcoat film. 15: A multicoat paint system produced by the method asclaimed in claim
 14. 16. (canceled) 17: The aqueouspolyurethane-polyurea dispersion of claim 1, wherein the composition hasa total content of less than 10% of N-methyl-2-pyrrolidone,dimethylformamide, dioxane, tetrahydrofuran, and/orN-ethyl-2-pyrrolidone, or wherein the composition does not comprise anyof N-methyl-2-pyrrolidone, dimethylformamide, dioxane, tetrahydrofuran,and N-ethyl-2-pyrrolidone. 18: The pigmented aqueous basecoat materialof claim 11, wherein a content of inorganic phyllosilicates if presentin the basecoat material is less than 0.5 wt %, or wherein the basecoatmaterial does not comprise inorganic phyllosilicates.